// -*- C++ -*-
//===-------------------------- iterator ----------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_ITERATOR
#define _LIBCPP_ITERATOR

/*
    iterator synopsis

namespace std
{

template<class Iterator>
struct iterator_traits
{
    typedef typename Iterator::difference_type difference_type;
    typedef typename Iterator::value_type value_type;
    typedef typename Iterator::pointer pointer;
    typedef typename Iterator::reference reference;
    typedef typename Iterator::iterator_category iterator_category;
};

template<class T>
struct iterator_traits<T*>
{
    typedef ptrdiff_t difference_type;
    typedef T value_type;
    typedef T* pointer;
    typedef T& reference;
    typedef random_access_iterator_tag iterator_category;
};

template<class T>
struct iterator_traits<const T*>
{
    typedef ptrdiff_t difference_type;
    typedef T value_type;
    typedef const T* pointer;
    typedef const T& reference;
    typedef random_access_iterator_tag iterator_category;
};

template<class Category, class T, class Distance = ptrdiff_t,
         class Pointer = T*, class Reference = T&>
struct iterator
{
    typedef T         value_type;
    typedef Distance  difference_type;
    typedef Pointer   pointer;
    typedef Reference reference;
    typedef Category  iterator_category;
};

struct input_iterator_tag  {};
struct output_iterator_tag {};
struct forward_iterator_tag       : public input_iterator_tag         {};
struct bidirectional_iterator_tag : public forward_iterator_tag       {};
struct random_access_iterator_tag : public bidirectional_iterator_tag {};

// extension: second argument not conforming to C++03
template <class InputIterator>
void advance(InputIterator& i,
             typename iterator_traits<InputIterator>::difference_type n);

template <class InputIterator>
typename iterator_traits<InputIterator>::difference_type
distance(InputIterator first, InputIterator last);

template <class Iterator>
class reverse_iterator
    : public iterator<typename iterator_traits<Iterator>::iterator_category,
                      typename iterator_traits<Iterator>::value_type,
                      typename iterator_traits<Iterator>::difference_type,
                      typename iterator_traits<Iterator>::pointer,
                      typename iterator_traits<Iterator>::reference>
{
protected:
    Iterator current;
public:
    typedef Iterator                                            iterator_type;
    typedef typename iterator_traits<Iterator>::difference_type difference_type;
    typedef typename iterator_traits<Iterator>::reference       reference;
    typedef typename iterator_traits<Iterator>::pointer         pointer;
    
    reverse_iterator();
    explicit reverse_iterator(Iterator x);
    template <class U> reverse_iterator(const reverse_iterator<U>& u);
    Iterator base() const;
    reference operator*() const;
    pointer   operator->() const;
    reverse_iterator& operator++();
    reverse_iterator  operator++(int);
    reverse_iterator& operator--();
    reverse_iterator  operator--(int);
    reverse_iterator  operator+ (difference_type n) const;
    reverse_iterator& operator+=(difference_type n);
    reverse_iterator  operator- (difference_type n) const;
    reverse_iterator& operator-=(difference_type n);
    reference         operator[](difference_type n) const;
};

template <class Iterator1, class Iterator2>
bool
operator==(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator1, class Iterator2>
bool
operator<(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator1, class Iterator2>
bool
operator!=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator1, class Iterator2>
bool
operator>(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator1, class Iterator2>
bool
operator>=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator1, class Iterator2>
bool
operator<=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator1, class Iterator2>
typename reverse_iterator<Iterator1>::difference_type
operator-(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);

template <class Iterator>
reverse_iterator<Iterator>
operator+(typename reverse_iterator<Iterator>::difference_type n, const reverse_iterator<Iterator>& x);

template <class Container>
class back_insert_iterator
{
protected:
    Container* container;
public:
    typedef Container                   container_type;
    typedef void                        value_type;
    typedef void                        difference_type;
    typedef back_insert_iterator<Cont>& reference;
    typedef void                        pointer;

    explicit back_insert_iterator(Container& x);
    back_insert_iterator& operator=(typename Container::const_reference value);
    back_insert_iterator& operator*();
    back_insert_iterator& operator++();
    back_insert_iterator  operator++(int);
};

template <class Container> back_insert_iterator<Container> back_inserter(Container& x);

template <class Container>
class front_insert_iterator
{
protected:
    Container* container;
public:
    typedef Container                    container_type;
    typedef void                         value_type;
    typedef void                         difference_type;
    typedef front_insert_iterator<Cont>& reference;
    typedef void                         pointer;

    explicit front_insert_iterator(Container& x);
    front_insert_iterator& operator=(typename Container::const_reference value);
    front_insert_iterator& operator*();
    front_insert_iterator& operator++();
    front_insert_iterator  operator++(int);
};

template <class Container> front_insert_iterator<Container> front_inserter(Container& x);

template <class Container>
class insert_iterator
{
protected:
    Container* container;
    typename Container::iterator iter;
public:
    typedef Container              container_type;
    typedef void                   value_type;
    typedef void                   difference_type;
    typedef insert_iterator<Cont>& reference;
    typedef void                   pointer;

    insert_iterator(Container& x, typename Container::iterator i);
    insert_iterator& operator=(typename Container::const_reference value);
    insert_iterator& operator*();
    insert_iterator& operator++();
    insert_iterator& operator++(int);
};

template <class Container, class Iterator>
insert_iterator<Container> inserter(Container& x, Iterator i);

template <class T, class charT = char, class traits = char_traits<charT>, class Distance = ptrdiff_t>
class istream_iterator
    : public iterator<input_iterator_tag, T, Distance, const T*, const T&>
{
public:
    typedef charT char_type;
    typedef traits traits_type;
    typedef basic_istream<charT,traits> istream_type;

    istream_iterator();
    istream_iterator(istream_type& s);
    istream_iterator(const istream_iterator& x);
    ~istream_iterator();

    const T& operator*() const;
    const T* operator->() const;
    istream_iterator& operator++();
    istream_iterator  operator++(int);
};

template <class T, class charT, class traits, class Distance>
bool operator==(const istream_iterator<T,charT,traits,Distance>& x,
                const istream_iterator<T,charT,traits,Distance>& y);
template <class T, class charT, class traits, class Distance>
bool operator!=(const istream_iterator<T,charT,traits,Distance>& x,
                const istream_iterator<T,charT,traits,Distance>& y);

template <class T, class charT = char, class traits = char_traits<charT> >
class ostream_iterator
    : public iterator<output_iterator_tag, void, void, void ,void>
{
public:
    typedef charT char_type;
    typedef traits traits_type;
    typedef basic_ostream<charT,traits> ostream_type;

    ostream_iterator(ostream_type& s);
    ostream_iterator(ostream_type& s, const charT* delimiter);
    ostream_iterator(const ostream_iterator& x);
    ~ostream_iterator();
    ostream_iterator& operator=(const T& value);

    ostream_iterator& operator*();
    ostream_iterator& operator++();
    ostream_iterator& operator++(int);
};

template<class charT, class traits = char_traits<charT> >
class istreambuf_iterator
    : public iterator<input_iterator_tag, charT,
                      typename traits::off_type, unspecified,
                      charT>
{
public:
    typedef charT                         char_type;
    typedef traits                        traits_type;
    typedef typename traits::int_type     int_type;
    typedef basic_streambuf<charT,traits> streambuf_type;
    typedef basic_istream<charT,traits>   istream_type;

    istreambuf_iterator() throw();
    istreambuf_iterator(istream_type& s) throw();
    istreambuf_iterator(streambuf_type* s) throw();
    istreambuf_iterator(a-private-type) throw();

    charT                operator*() const;
    pointer operator->() const;
    istreambuf_iterator& operator++();
    a-private-type       operator++(int);

    bool equal(const istreambuf_iterator& b) const;
};

template <class charT, class traits>
bool operator==(const istreambuf_iterator<charT,traits>& a,
                const istreambuf_iterator<charT,traits>& b);
template <class charT, class traits>
bool operator!=(const istreambuf_iterator<charT,traits>& a,
                const istreambuf_iterator<charT,traits>& b);

template <class charT, class traits = char_traits<charT> >
class ostreambuf_iterator
    : public iterator<output_iterator_tag, void, void, void, void>
{
public:
    typedef charT                         char_type;
    typedef traits                        traits_type;
    typedef basic_streambuf<charT,traits> streambuf_type;
    typedef basic_ostream<charT,traits>   ostream_type;

    ostreambuf_iterator(ostream_type& s) throw();
    ostreambuf_iterator(streambuf_type* s) throw();
    ostreambuf_iterator& operator=(charT c);
    ostreambuf_iterator& operator*();
    ostreambuf_iterator& operator++();
    ostreambuf_iterator& operator++(int);
    bool failed() const throw();
};

template <class C> auto begin(C& c) -> decltype(c.begin());
template <class C> auto begin(const C& c) -> decltype(c.begin());
template <class C> auto end(C& c) -> decltype(c.end());
template <class C> auto end(const C& c) -> decltype(c.end());
template <class T, size_t N> T* begin(T (&array)[N]);
template <class T, size_t N> T* end(T (&array)[N]);

}  // std

*/

#include <__config>
#include <type_traits>
#include <cstddef>
#include <iosfwd>
#ifdef _LIBCPP_DEBUG
#include <cassert>
#endif

#pragma GCC system_header

_LIBCPP_BEGIN_NAMESPACE_STD

struct input_iterator_tag {};
struct output_iterator_tag {};
struct forward_iterator_tag       : public input_iterator_tag {};
struct bidirectional_iterator_tag : public forward_iterator_tag {};
struct random_access_iterator_tag : public bidirectional_iterator_tag {};

template <class _Tp>
struct __has_iterator_category
{
private:
    struct __two {char _; char __;};
    template <class _Up> static __two __test(...);
    template <class _Up> static char __test(typename _Up::iterator_category* = 0);
public:
    static const bool value = sizeof(__test<_Tp>(0)) == 1;
};

template <class _Iter, bool> struct ____iterator_traits {};

template <class _Iter>
struct ____iterator_traits<_Iter, true>
{
    typedef typename _Iter::difference_type   difference_type;
    typedef typename _Iter::value_type        value_type;
    typedef typename _Iter::pointer           pointer;
    typedef typename _Iter::reference         reference;
    typedef typename _Iter::iterator_category iterator_category;
};

template <class _Iter, bool> struct __iterator_traits {};

template <class _Iter>
struct __iterator_traits<_Iter, true>
    :  ____iterator_traits
      <
        _Iter,
        is_convertible<typename _Iter::iterator_category, input_iterator_tag>::value ||
        is_convertible<typename _Iter::iterator_category, output_iterator_tag>::value
      >
{};

// iterator_traits<Iterator> will only have the nested types if Iterator::iterator_category
//    exists.  Else iterator_traits<Iterator> will be an empty class.  This is a
//    conforming extension which allows some programs to compile and behave as
//    the client expects instead of failing at compile time.

template <class _Iter>
struct iterator_traits
    : __iterator_traits<_Iter, __has_iterator_category<_Iter>::value> {};

template<class _Tp>
struct iterator_traits<_Tp*>
{
    typedef ptrdiff_t difference_type;
    typedef typename remove_const<_Tp>::type value_type;
    typedef _Tp* pointer;
    typedef _Tp& reference;
    typedef random_access_iterator_tag iterator_category;
};

template <class _Tp, class _Up, bool = __has_iterator_category<iterator_traits<_Tp> >::value>
struct __has_iterator_category_convertible_to
    : public integral_constant<bool, is_convertible<typename iterator_traits<_Tp>::iterator_category, _Up>::value>
{};

template <class _Tp, class _Up>
struct __has_iterator_category_convertible_to<_Tp, _Up, false> : public false_type {};

template <class _Tp>
struct __is_input_iterator : public __has_iterator_category_convertible_to<_Tp, input_iterator_tag> {};

template <class _Tp>
struct __is_forward_iterator : public __has_iterator_category_convertible_to<_Tp, forward_iterator_tag> {};

template <class _Tp>
struct __is_bidirectional_iterator : public __has_iterator_category_convertible_to<_Tp, bidirectional_iterator_tag> {};

template <class _Tp>
struct __is_random_access_iterator : public __has_iterator_category_convertible_to<_Tp, random_access_iterator_tag> {};

template<class _Category, class _Tp, class _Distance = ptrdiff_t,
         class _Pointer = _Tp*, class _Reference = _Tp&>
struct iterator
{
    typedef _Tp        value_type;
    typedef _Distance  difference_type;
    typedef _Pointer   pointer;
    typedef _Reference reference;
    typedef _Category  iterator_category;
};

template <class _InputIter>
inline _LIBCPP_INLINE_VISIBILITY
void __advance(_InputIter& __i,
             typename iterator_traits<_InputIter>::difference_type __n, input_iterator_tag)
{
    for (; __n > 0; --__n)
        ++__i;
}

template <class _BiDirIter>
inline _LIBCPP_INLINE_VISIBILITY
void __advance(_BiDirIter& __i,
             typename iterator_traits<_BiDirIter>::difference_type __n, bidirectional_iterator_tag)
{
    if (__n >= 0)
        for (; __n > 0; --__n)
            ++__i;
    else
        for (; __n < 0; ++__n)
            --__i;
}

template <class _RandIter>
inline _LIBCPP_INLINE_VISIBILITY
void __advance(_RandIter& __i,
             typename iterator_traits<_RandIter>::difference_type __n, random_access_iterator_tag)
{
   __i += __n;
}

template <class _InputIter>
inline _LIBCPP_INLINE_VISIBILITY
void advance(_InputIter& __i,
             typename iterator_traits<_InputIter>::difference_type __n)
{
    __advance(__i, __n, typename iterator_traits<_InputIter>::iterator_category());
}

template <class _InputIter>
inline _LIBCPP_INLINE_VISIBILITY
typename iterator_traits<_InputIter>::difference_type
__distance(_InputIter __first, _InputIter __last, input_iterator_tag)
{
    typename iterator_traits<_InputIter>::difference_type __r(0);
    for (; __first != __last; ++__first)
        ++__r;
    return __r;
}

template <class _RandIter>
inline _LIBCPP_INLINE_VISIBILITY
typename iterator_traits<_RandIter>::difference_type
__distance(_RandIter __first, _RandIter __last, random_access_iterator_tag)
{
    return __last - __first;
}

template <class _InputIter>
inline _LIBCPP_INLINE_VISIBILITY
typename iterator_traits<_InputIter>::difference_type
distance(_InputIter __first, _InputIter __last)
{
    return __distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
}

template <class _ForwardIter>
inline
_ForwardIter
next(_ForwardIter __x,
     typename iterator_traits<_ForwardIter>::difference_type __n = 1,
     typename enable_if<__is_forward_iterator<_ForwardIter>::value>::type* = 0)
{
    advance(__x, __n);
    return __x;
}

template <class _BidiretionalIter>
inline
_BidiretionalIter
prev(_BidiretionalIter __x,
     typename iterator_traits<_BidiretionalIter>::difference_type __n = 1,
     typename enable_if<__is_bidirectional_iterator<_BidiretionalIter>::value>::type* = 0)
{
    advance(__x, -__n);
    return __x;
}

template <class _Iter>
class reverse_iterator
    : public iterator<typename iterator_traits<_Iter>::iterator_category,
                      typename iterator_traits<_Iter>::value_type,
                      typename iterator_traits<_Iter>::difference_type,
                      typename iterator_traits<_Iter>::pointer,
                      typename iterator_traits<_Iter>::reference>
{
private:
    mutable _Iter __t;
protected:
    _Iter current;
public:
    typedef _Iter                                            iterator_type;
    typedef typename iterator_traits<_Iter>::difference_type difference_type;
    typedef typename iterator_traits<_Iter>::reference       reference;
    typedef typename iterator_traits<_Iter>::pointer         pointer;
    
    _LIBCPP_INLINE_VISIBILITY reverse_iterator() : current() {}
    _LIBCPP_INLINE_VISIBILITY explicit reverse_iterator(_Iter __x) : __t(__x), current(__x) {}
    template <class _Up> _LIBCPP_INLINE_VISIBILITY reverse_iterator(const reverse_iterator<_Up>& __u)
        : __t(__u.base()), current(__u.base()) {}
    _LIBCPP_INLINE_VISIBILITY _Iter base() const {return current;}
    _LIBCPP_INLINE_VISIBILITY reference operator*() const {__t = current; return *--__t;}
    _LIBCPP_INLINE_VISIBILITY pointer  operator->() const {return &(operator*());}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator& operator++() {--current; return *this;}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator  operator++(int)
        {reverse_iterator __tmp(*this); --current; return __tmp;}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator& operator--() {++current; return *this;}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator  operator--(int)
        {reverse_iterator __tmp(*this); ++current; return __tmp;}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator  operator+ (difference_type __n) const
        {return reverse_iterator(current - __n);}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator& operator+=(difference_type __n)
        {current -= __n; return *this;}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator  operator- (difference_type __n) const
        {return reverse_iterator(current + __n);}
    _LIBCPP_INLINE_VISIBILITY reverse_iterator& operator-=(difference_type __n)
        {current += __n; return *this;}
    _LIBCPP_INLINE_VISIBILITY reference         operator[](difference_type __n) const
        {return current[-__n-1];}
};

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __x.base() == __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __x.base() > __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __x.base() != __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __x.base() < __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __x.base() <= __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __x.base() >= __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
typename reverse_iterator<_Iter1>::difference_type
operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
    return __y.base() - __x.base();
}

template <class _Iter>
inline _LIBCPP_INLINE_VISIBILITY
reverse_iterator<_Iter>
operator+(typename reverse_iterator<_Iter>::difference_type __n, const reverse_iterator<_Iter>& __x)
{
    return reverse_iterator<_Iter>(__x.base() - __n);
}

template <class _Container>
class back_insert_iterator
    : public iterator<output_iterator_tag,
                      void,
                      void,
                      void,
                      back_insert_iterator<_Container>&>
{
protected:
    _Container* container;
public:
    typedef _Container container_type;

    _LIBCPP_INLINE_VISIBILITY explicit back_insert_iterator(_Container& __x) : container(&__x) {}
    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator=(typename _Container::const_reference __value)
        {container->push_back(__value); return *this;}
#ifdef _LIBCPP_MOVE
    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator=(typename _Container::value_type&& __value)
        {container->push_back(_STD::move(__value)); return *this;}
#endif
    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator*()     {return *this;}
    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator++()    {return *this;}
    _LIBCPP_INLINE_VISIBILITY back_insert_iterator  operator++(int) {return *this;}
};

template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
back_insert_iterator<_Container>
back_inserter(_Container& __x)
{
    return back_insert_iterator<_Container>(__x);
}

template <class _Container>
class front_insert_iterator
    : public iterator<output_iterator_tag,
                      void,
                      void,
                      void,
                      front_insert_iterator<_Container>&>
{
protected:
    _Container* container;
public:
    typedef _Container container_type;

    _LIBCPP_INLINE_VISIBILITY explicit front_insert_iterator(_Container& __x) : container(&__x) {}
    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator=(typename _Container::const_reference __value)
        {container->push_front(__value); return *this;}
#ifdef _LIBCPP_MOVE
    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator=(typename _Container::value_type&& __value)
        {container->push_front(_STD::move(__value)); return *this;}
#endif
    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator*()     {return *this;}
    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator++()    {return *this;}
    _LIBCPP_INLINE_VISIBILITY front_insert_iterator  operator++(int) {return *this;}
};

template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
front_insert_iterator<_Container>
front_inserter(_Container& __x)
{
    return front_insert_iterator<_Container>(__x);
}

template <class _Container>
class insert_iterator
    : public iterator<output_iterator_tag,
                      void,
                      void,
                      void,
                      insert_iterator<_Container>&>
{
protected:
    _Container* container;
    typename _Container::iterator iter;
public:
    typedef _Container container_type;

    _LIBCPP_INLINE_VISIBILITY insert_iterator(_Container& __x, typename _Container::iterator __i)
        : container(&__x), iter(__i) {}
    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator=(typename _Container::const_reference __value)
        {iter = container->insert(iter, __value); ++iter; return *this;}
#ifdef _LIBCPP_MOVE
    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator=(typename _Container::value_type&& __value)
        {iter = container->insert(iter, _STD::move(__value)); ++iter; return *this;}
#endif
    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator*()        {return *this;}
    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator++()       {return *this;}
    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator++(int)    {return *this;}
};

template <class _Container>
inline _LIBCPP_INLINE_VISIBILITY
insert_iterator<_Container>
inserter(_Container& __x, typename _Container::iterator __i)
{
    return insert_iterator<_Container>(__x, __i);
}

template <class _Tp, class _CharT = char,
          class _Traits = char_traits<_CharT>, class _Distance = ptrdiff_t>
class istream_iterator
    : public iterator<input_iterator_tag, _Tp, _Distance, const _Tp*, const _Tp&>
{
public:
    typedef _CharT char_type;
    typedef _Traits traits_type;
    typedef basic_istream<_CharT,_Traits> istream_type;
private:
    istream_type* __in_stream_;
    _Tp __value_;
public:
    _LIBCPP_INLINE_VISIBILITY istream_iterator() : __in_stream_(0) {}
    _LIBCPP_INLINE_VISIBILITY istream_iterator(istream_type& __s) : __in_stream_(&__s)
        {
            if (!(*__in_stream_ >> __value_))
                __in_stream_ = 0;
        }

    _LIBCPP_INLINE_VISIBILITY const _Tp& operator*() const {return __value_;}
    _LIBCPP_INLINE_VISIBILITY const _Tp* operator->() const {return &(operator*());}
    _LIBCPP_INLINE_VISIBILITY istream_iterator& operator++()
        {
            if (!(*__in_stream_ >> __value_))
                __in_stream_ = 0;
            return *this;
        }
    _LIBCPP_INLINE_VISIBILITY istream_iterator  operator++(int)
        {istream_iterator __t(*this); ++(*this); return __t;}

    friend _LIBCPP_INLINE_VISIBILITY
    bool operator==(const istream_iterator& __x, const istream_iterator& __y)
        {return __x.__in_stream_ == __y.__in_stream_;}

    friend _LIBCPP_INLINE_VISIBILITY
    bool operator!=(const istream_iterator& __x, const istream_iterator& __y)
        {return !(__x == __y);}
};

template <class _Tp, class _CharT = char, class _Traits = char_traits<_CharT> >
class ostream_iterator
    : public iterator<output_iterator_tag, void, void, void, void>
{
public:
    typedef _CharT char_type;
    typedef _Traits traits_type;
    typedef basic_ostream<_CharT,_Traits> ostream_type;
private:
    ostream_type* __out_stream_;
    const char_type* __delim_;
public:
    _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s)
        : __out_stream_(&__s), __delim_(0) {}
    _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s, const _CharT* __delimiter)
        : __out_stream_(&__s), __delim_(__delimiter) {}
    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator=(const _Tp& __value)
        {
            *__out_stream_ << __value;
            if (__delim_)
                *__out_stream_ << __delim_;
            return *this;
        }

    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator*()     {return *this;}
    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator++()    {return *this;}
    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator++(int) {return *this;}
};

template<class _CharT, class _Traits>
class istreambuf_iterator
    : public iterator<input_iterator_tag, _CharT,
                      typename _Traits::off_type, _CharT*,
                      _CharT>
{
public:
    typedef _CharT                          char_type;
    typedef _Traits                         traits_type;
    typedef typename _Traits::int_type      int_type;
    typedef basic_streambuf<_CharT,_Traits> streambuf_type;
    typedef basic_istream<_CharT,_Traits>   istream_type;
private:
    streambuf_type* __sbuf_;

    class __proxy
    {
        char_type __keep_;
        streambuf_type* __sbuf_;
        _LIBCPP_INLINE_VISIBILITY __proxy(char_type __c, streambuf_type* __s)
            : __keep_(__c), __sbuf_(__s) {}
        friend class istreambuf_iterator;
    public:
        _LIBCPP_INLINE_VISIBILITY char_type operator*() const {return __keep_;}
    };

    void __test_for_eof()
    {
        if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
            __sbuf_ = 0;
    }
public:
    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator() throw() : __sbuf_(0) {}
    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) throw()
        : __sbuf_(__s.rdbuf()) {__test_for_eof();}
    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) throw()
        : __sbuf_(__s) {__test_for_eof();}
    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(const __proxy& __p) throw()
        : __sbuf_(__p.__sbuf_) {}

    _LIBCPP_INLINE_VISIBILITY _CharT               operator*() const {return __sbuf_->sgetc();}
    _LIBCPP_INLINE_VISIBILITY char_type* operator->() const {return nullptr;}
    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator& operator++()
        {
            if (traits_type::eq_int_type(__sbuf_->snextc(), traits_type::eof()))
                __sbuf_ = 0;
            return *this;
        }
    _LIBCPP_INLINE_VISIBILITY __proxy              operator++(int)
        {
            char_type __c = __sbuf_->sgetc();
            ++(*this);
            return __proxy(__c, __sbuf_);
        }

    _LIBCPP_INLINE_VISIBILITY bool equal(const istreambuf_iterator& __b) const
        {return (__sbuf_ == 0) == (__b.__sbuf_ == 0);}
};

template <class _CharT, class _Traits>
inline _LIBCPP_INLINE_VISIBILITY
bool operator==(const istreambuf_iterator<_CharT,_Traits>& __a,
                const istreambuf_iterator<_CharT,_Traits>& __b)
                {return __a.equal(__b);}

template <class _CharT, class _Traits>
inline _LIBCPP_INLINE_VISIBILITY
bool operator!=(const istreambuf_iterator<_CharT,_Traits>& __a,
                const istreambuf_iterator<_CharT,_Traits>& __b)
                {return !__a.equal(__b);}

template <class _CharT, class _Traits>
class ostreambuf_iterator
    : public iterator<output_iterator_tag, void, void, void, void>
{
public:
    typedef _CharT                          char_type;
    typedef _Traits                         traits_type;
    typedef basic_streambuf<_CharT,_Traits> streambuf_type;
    typedef basic_ostream<_CharT,_Traits>   ostream_type;
private:
    streambuf_type* __sbuf_;
public:
    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator(ostream_type& __s) throw()
        : __sbuf_(__s.rdbuf()) {}
    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator(streambuf_type* __s) throw()
        : __sbuf_(__s) {}
    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator=(_CharT __c)
        {
            if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sputc(__c), traits_type::eof()))
                __sbuf_ = 0;
            return *this;
        }
    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator*()     {return *this;}
    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++()    {return *this;}
    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
    _LIBCPP_INLINE_VISIBILITY bool failed() const throw() {return __sbuf_ == 0;}
};

template <class _Iter>
class move_iterator
{
private:
    _Iter __i;
public:
    typedef _Iter                                            iterator_type;
    typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
    typedef typename iterator_traits<iterator_type>::value_type value_type;
    typedef typename iterator_traits<iterator_type>::difference_type difference_type;
    typedef typename iterator_traits<iterator_type>::pointer pointer;
#ifdef _LIBCPP_MOVE
    typedef value_type&& reference;
#else
    typedef typename iterator_traits<iterator_type>::reference reference;
#endif
    
    _LIBCPP_INLINE_VISIBILITY move_iterator() : __i() {}
    _LIBCPP_INLINE_VISIBILITY explicit move_iterator(_Iter __x) : __i(__x) {}
    template <class _Up> _LIBCPP_INLINE_VISIBILITY move_iterator(const move_iterator<_Up>& __u)
        : __i(__u.base()) {}
    _LIBCPP_INLINE_VISIBILITY _Iter base() const {return __i;}
    _LIBCPP_INLINE_VISIBILITY reference operator*() const {return *__i;}
    _LIBCPP_INLINE_VISIBILITY pointer  operator->() const {return &(operator*());}
    _LIBCPP_INLINE_VISIBILITY move_iterator& operator++() {++__i; return *this;}
    _LIBCPP_INLINE_VISIBILITY move_iterator  operator++(int)
        {move_iterator __tmp(*this); ++__i; return __tmp;}
    _LIBCPP_INLINE_VISIBILITY move_iterator& operator--() {--__i; return *this;}
    _LIBCPP_INLINE_VISIBILITY move_iterator  operator--(int)
        {move_iterator __tmp(*this); --__i; return __tmp;}
    _LIBCPP_INLINE_VISIBILITY move_iterator  operator+ (difference_type __n) const
        {return move_iterator(__i + __n);}
    _LIBCPP_INLINE_VISIBILITY move_iterator& operator+=(difference_type __n)
        {__i += __n; return *this;}
    _LIBCPP_INLINE_VISIBILITY move_iterator  operator- (difference_type __n) const
        {return move_iterator(__i - __n);}
    _LIBCPP_INLINE_VISIBILITY move_iterator& operator-=(difference_type __n)
        {__i -= __n; return *this;}
    _LIBCPP_INLINE_VISIBILITY reference         operator[](difference_type __n) const
        {return __i[__n];}
};

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() == __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() < __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() != __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() > __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() >= __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() <= __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
typename move_iterator<_Iter1>::difference_type
operator-(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
{
    return __x.base() - __y.base();
}

template <class _Iter>
inline _LIBCPP_INLINE_VISIBILITY
move_iterator<_Iter>
operator+(typename move_iterator<_Iter>::difference_type __n, const move_iterator<_Iter>& __x)
{
    return move_iterator<_Iter>(__x.base() + __n);
}

template <class _Iter>
inline _LIBCPP_INLINE_VISIBILITY
move_iterator<_Iter>
make_move_iterator(const _Iter& __i)
{
    return move_iterator<_Iter>(__i);
}

// __wrap_iter

template <class _Iter> class __wrap_iter;

template <class _Iter1, class _Iter2>
bool
operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter1, class _Iter2>
bool
operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter1, class _Iter2>
bool
operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter1, class _Iter2>
bool
operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter1, class _Iter2>
bool
operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter1, class _Iter2>
bool
operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter1, class _Iter2>
typename __wrap_iter<_Iter1>::difference_type
operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);

template <class _Iter>
__wrap_iter<_Iter>
operator+(typename __wrap_iter<_Iter>::difference_type, const __wrap_iter<_Iter>&);

template <class _I, class _O> _O copy(_I, _I, _O);
template <class _B1, class _B2> _B2 copy_backward(_B1, _B1, _B2);
template <class _I, class _O> _O move(_I, _I, _O);
template <class _B1, class _B2> _B2 move_backward(_B1, _B1, _B2);

template <class _Tp>
typename enable_if
<
    has_trivial_copy_assign<_Tp>::value,
    _Tp*
>::type
__unwrap_iter(__wrap_iter<_Tp*>);

template <class _Iter>
class __wrap_iter
{
public:
    typedef _Iter                                                      iterator_type;
    typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
    typedef typename iterator_traits<iterator_type>::value_type        value_type;
    typedef typename iterator_traits<iterator_type>::difference_type   difference_type;
    typedef typename iterator_traits<iterator_type>::pointer           pointer;
    typedef typename iterator_traits<iterator_type>::reference         reference;
private:
    iterator_type __i;
public:
    _LIBCPP_INLINE_VISIBILITY __wrap_iter() {}
    template <class _Up> _LIBCPP_INLINE_VISIBILITY __wrap_iter(const __wrap_iter<_Up>& __u,
        typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = 0)
        : __i(__u.base()) {}
    _LIBCPP_INLINE_VISIBILITY reference operator*() const {return *__i;}
    _LIBCPP_INLINE_VISIBILITY pointer  operator->() const {return &(operator*());}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter& operator++() {++__i; return *this;}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter  operator++(int)
        {__wrap_iter __tmp(*this); ++__i; return __tmp;}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter& operator--() {--__i; return *this;}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter  operator--(int)
        {__wrap_iter __tmp(*this); --__i; return __tmp;}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter  operator+ (difference_type __n) const
        {return __wrap_iter(__i + __n);}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter& operator+=(difference_type __n)
        {__i += __n; return *this;}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter  operator- (difference_type __n) const
        {return __wrap_iter(__i - __n);}
    _LIBCPP_INLINE_VISIBILITY __wrap_iter& operator-=(difference_type __n)
        {__i -= __n; return *this;}
    _LIBCPP_INLINE_VISIBILITY reference        operator[](difference_type __n) const
        {return __i[__n];}

    _LIBCPP_INLINE_VISIBILITY iterator_type base() const {return __i;}

private:
    _LIBCPP_INLINE_VISIBILITY __wrap_iter(iterator_type __x) : __i(__x) {}

    template <class _Up> friend class __wrap_iter;
    template <class _CharT, class _Traits, class _Alloc> friend class basic_string;
    template <class _Tp, class _Alloc> friend class vector;

    template <class _Iter1, class _Iter2>
    friend
    bool
    operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1, class _Iter2>
    friend
    bool
    operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1, class _Iter2>
    friend
    bool
    operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1, class _Iter2>
    friend
    bool
    operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1, class _Iter2>
    friend
    bool
    operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1, class _Iter2>
    friend
    bool
    operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1, class _Iter2>
    friend
    typename __wrap_iter<_Iter1>::difference_type
    operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&);
    
    template <class _Iter1>
    friend
    __wrap_iter<_Iter1>
    operator+(typename __wrap_iter<_Iter1>::difference_type, const __wrap_iter<_Iter1>&);

    template <class _I, class _O> friend _O copy(_I, _I, _O);
    template <class _B1, class _B2> friend _B2 copy_backward(_B1, _B1, _B2);
    template <class _I, class _O> friend _O move(_I, _I, _O);
    template <class _B1, class _B2> friend _B2 move_backward(_B1, _B1, _B2);

    template <class _Tp>
    friend
    typename enable_if
    <
        has_trivial_copy_assign<_Tp>::value,
        _Tp*
    >::type
    __unwrap_iter(__wrap_iter<_Tp*>);
};

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() == __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() < __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() != __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() > __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() >= __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() <= __y.base();
}

template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
typename __wrap_iter<_Iter1>::difference_type
operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y)
{
    return __x.base() - __y.base();
}

template <class _Iter>
inline _LIBCPP_INLINE_VISIBILITY
__wrap_iter<_Iter>
operator+(typename __wrap_iter<_Iter>::difference_type __n,
          const __wrap_iter<_Iter>& __x)
{
    return __wrap_iter<_Iter>(__x.base() + __n);
}

#ifdef _LIBCPP_DEBUG

// __debug_iter

template <class _Container, class _Iter> class __debug_iter;

template <class _Container, class _Iter1, class _Iter2>
bool
operator==(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter1, class _Iter2>
bool
operator<(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter1, class _Iter2>
bool
operator!=(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter1, class _Iter2>
bool
operator>(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter1, class _Iter2>
bool
operator>=(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter1, class _Iter2>
bool
operator<=(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter1, class _Iter2>
typename __debug_iter<_Container, _Iter1>::difference_type
operator-(const __debug_iter<_Container, _Iter1>&, const __debug_iter<_Container, _Iter2>&);

template <class _Container, class _Iter>
__debug_iter<_Container, _Iter>
operator+(typename __debug_iter<_Container, _Iter>::difference_type, const __debug_iter<_Container, _Iter>&);

template <class _Container, class _Iter>
class __debug_iter
{
public:
    typedef _Iter                                                      iterator_type;
    typedef _Container                                                 __container_type;
    typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
    typedef typename iterator_traits<iterator_type>::value_type        value_type;
    typedef typename iterator_traits<iterator_type>::difference_type   difference_type;
    typedef typename iterator_traits<iterator_type>::pointer           pointer;
    typedef typename iterator_traits<iterator_type>::reference         reference;
private:
    iterator_type __i;
    __debug_iter* __next;
    __container_type* __cont;
    
public:
    _LIBCPP_INLINE_VISIBILITY __debug_iter() : __next(0), __cont(0) {}
    _LIBCPP_INLINE_VISIBILITY __debug_iter(const __debug_iter& __x)
        : __i(__x.base()), __next(0), __cont(0) {__set_owner(__x.__cont);}
    __debug_iter& operator=(const __debug_iter& __x);
    template <class _Up> _LIBCPP_INLINE_VISIBILITY __debug_iter(const __debug_iter<_Container, _Up>& __u,
        typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = 0)
        : __i(__u.base()), __next(0), __cont(0) {__set_owner(__u.__cont);}
    _LIBCPP_INLINE_VISIBILITY ~__debug_iter() {__remove_owner();}
    _LIBCPP_INLINE_VISIBILITY reference operator*() const {assert(__is_deref()); return *__i;}
    _LIBCPP_INLINE_VISIBILITY pointer  operator->() const {return &(operator*());}
    _LIBCPP_INLINE_VISIBILITY __debug_iter& operator++() {assert(__can_increment()); ++__i; return *this;}
    _LIBCPP_INLINE_VISIBILITY __debug_iter  operator++(int)
        {__debug_iter __tmp(*this); operator++(); return __tmp;}
    _LIBCPP_INLINE_VISIBILITY __debug_iter& operator--() {assert(__can_decrement()); --__i; return *this;}
    _LIBCPP_INLINE_VISIBILITY __debug_iter  operator--(int)
        {__debug_iter __tmp(*this); operator--(); return __tmp;}
    _LIBCPP_INLINE_VISIBILITY __debug_iter  operator+ (difference_type __n) const
        {__debug_iter __t(*this); __t += __n; return __t;}
    __debug_iter& operator+=(difference_type __n);
    _LIBCPP_INLINE_VISIBILITY __debug_iter  operator- (difference_type __n) const
        {__debug_iter __t(*this); __t -= __n; return __t;}
    _LIBCPP_INLINE_VISIBILITY __debug_iter& operator-=(difference_type __n)
        {*this += -__n; return *this;}
    _LIBCPP_INLINE_VISIBILITY reference        operator[](difference_type __n) const
        {return *(*this + __n);}

private:
    _LIBCPP_INLINE_VISIBILITY __debug_iter(const __container_type* __c, iterator_type __x)
        : __i(__x), __next(0), __cont(0) {__set_owner(__c);}
    _LIBCPP_INLINE_VISIBILITY iterator_type base() const {return __i;}

    void __set_owner(const __container_type* __c);
    void __remove_owner();
    static void __remove_all(__container_type* __c);
    static void swap(__container_type* __x, __container_type* __y);
    
    _LIBCPP_INLINE_VISIBILITY bool __is_deref() const
        {return __is_deref(__is_random_access_iterator<iterator_type>());}
    bool __is_deref(false_type) const;
    bool __is_deref(true_type) const;
    _LIBCPP_INLINE_VISIBILITY bool __can_decrement() const
        {return __can_decrement(integral_constant<int, is_pointer<iterator_type>::value ? 2:
                                                       __is_random_access_iterator<iterator_type>::value ? 1 : 0>());}
    bool __can_decrement(integral_constant<int, 0>) const;
    bool __can_decrement(integral_constant<int, 1>) const;
    bool __can_decrement(integral_constant<int, 2>) const;
    _LIBCPP_INLINE_VISIBILITY bool __can_increment() const
        {return __can_increment(integral_constant<int, is_pointer<iterator_type>::value ? 2:
                                                       __is_random_access_iterator<iterator_type>::value ? 1 : 0>());}
    bool __can_increment(integral_constant<int, 0>) const;
    bool __can_increment(integral_constant<int, 1>) const;
    bool __can_increment(integral_constant<int, 2>) const;

    _LIBCPP_INLINE_VISIBILITY bool __can_add(difference_type __n) const
        {return __can_add(__n, is_pointer<iterator_type>());}
    bool __can_add(difference_type __n, false_type) const;
    bool __can_add(difference_type __n, true_type) const;

    template <class _Cp, class _Up> friend class __debug_iter;
    friend class _Container::__self;

    template <class _Cp, class _Iter1, class _Iter2>
    friend
    bool
    operator==(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1, class _Iter2>
    friend
    bool
    operator<(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1, class _Iter2>
    friend
    bool
    operator!=(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1, class _Iter2>
    friend
    bool
    operator>(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1, class _Iter2>
    friend
    bool
    operator>=(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1, class _Iter2>
    friend
    bool
    operator<=(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1, class _Iter2>
    friend
    typename __debug_iter<_Cp, _Iter1>::difference_type
    operator-(const __debug_iter<_Cp, _Iter1>&, const __debug_iter<_Cp, _Iter2>&);
    
    template <class _Cp, class _Iter1>
    friend
    __debug_iter<_Cp, _Iter1>
    operator+(typename __debug_iter<_Cp, _Iter1>::difference_type, const __debug_iter<_Cp, _Iter1>&);
};

template <class _Container, class _Iter>
__debug_iter<_Container, _Iter>&
__debug_iter<_Container, _Iter>::operator=(const __debug_iter& __x)
{
    if (this != &__x)
    {
        __remove_owner();
        __i = __x.__i;
        __set_owner(__x.__cont);
    }
    return *this;
}
    
template <class _Container, class _Iter>
void
__debug_iter<_Container, _Iter>::__set_owner(const __container_type* __c)
{
    __cont = const_cast<__container_type*>(__c);
    __debug_iter*& __head = __cont->__get_iterator_list(this);
    __next = __head;
    __head = this;
}

template <class _Container, class _Iter>
void
__debug_iter<_Container, _Iter>::__remove_owner()
{
    if (__cont)
    {
        __debug_iter*& __head = __cont->__get_iterator_list(this);
        if (__head == this)
            __head = __next;
        else
        {
            __debug_iter* __prev = __head;
            for (__debug_iter* __p = __head->__next; __p != this; __p = __p->__next)
                __prev = __p;
            __prev->__next = __next;
        }
        __cont = 0;
    }
}

template <class _Container, class _Iter>
void
__debug_iter<_Container, _Iter>::__remove_all(__container_type* __c)
{
    __debug_iter*& __head = __c->__get_iterator_list((__debug_iter*)0);
    __debug_iter* __p = __head;
    __head = 0;
    while (__p)
    {
        __p->__cont = 0;
        __debug_iter* __n = __p->__next;
        __p->__next = 0;
        __p = __n;
    }
}

template <class _Container, class _Iter>
void
__debug_iter<_Container, _Iter>::swap(__container_type* __x, __container_type* __y)
{
    __debug_iter*& __head_x = __x->__get_iterator_list((__debug_iter*)0);
    __debug_iter*& __head_y = __y->__get_iterator_list((__debug_iter*)0);
    __debug_iter* __p = __head_x;
    __head_x = __head_y;
    __head_y = __p;
    for (__p = __head_x; __p; __p = __p->__next)
        __p->__cont = __x;
    for (__p = __head_y; __p; __p = __p->__next)
        __p->__cont = __y;
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__is_deref(false_type) const
{
    if (__cont == 0)
        return false;
    return __i != __cont->end().base();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__is_deref(true_type) const
{
    if (__cont == 0)
        return false;
    return __i < __cont->end().base();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_decrement(integral_constant<int, 0>) const
{
    if (__cont == 0)
        return false;
    return __i != __cont->begin().base();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_decrement(integral_constant<int, 1>) const
{
    if (__cont == 0)
        return false;
    iterator_type __b = __cont->begin().base();
    return __b < __i && __i <= __b + __cont->size();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_decrement(integral_constant<int, 2>) const
{
    if (__cont == 0)
        return false;
    iterator_type __b = __cont->begin().base();
    return __b < __i && __i <= __b + __cont->size();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_increment(integral_constant<int, 0>) const
{
    if (__cont == 0)
        return false;
    return __i != __cont->end().base();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_increment(integral_constant<int, 1>) const
{
    if (__cont == 0)
        return false;
    iterator_type __b = __cont->begin().base();
    return __b <= __i && __i < __b + __cont->size();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_increment(integral_constant<int, 2>) const
{
    if (__cont == 0)
        return false;
    iterator_type __b = __cont->begin().base();
    return __b <= __i && __i < __b + __cont->size();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_add(difference_type __n, false_type) const
{
    if (__cont == 0)
        return false;
    iterator_type __b = __cont->begin().base();
    iterator_type __j = __i + __n;
    return __b <= __j && __j <= __b + __cont->size();
}

template <class _Container, class _Iter>
bool
__debug_iter<_Container, _Iter>::__can_add(difference_type __n, true_type) const
{
    if (__cont == 0)
        return false;
    iterator_type __b = __cont->begin().base();
    iterator_type __j = __i + __n;
    return __b <= __j && __j <= __b + __cont->size();
}

template <class _Container, class _Iter>
__debug_iter<_Container, _Iter>&
__debug_iter<_Container, _Iter>::operator+=(difference_type __n)
{
    assert(__can_add(__n));
    __i += __n;
    return *this;
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    assert(__x.__cont && __x.__cont == __y.__cont);
    return __x.base() == __y.base();
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    return !(__x == __y);
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    assert(__x.__cont && __x.__cont == __y.__cont);
    return __x.base() < __y.base();
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    return __y < __x;
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>=(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    return !(__x < __y);
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<=(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    return !(__y < __x);
}

template <class _Container, class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
typename __debug_iter<_Container, _Iter1>::difference_type
operator-(const __debug_iter<_Container, _Iter1>& __x, const __debug_iter<_Container, _Iter2>& __y)
{
    assert(__x.__cont && __x.__cont == __y.__cont);
    return __x.base() - __y.base();
}

template <class _Container, class _Iter>
inline _LIBCPP_INLINE_VISIBILITY
__debug_iter<_Container, _Iter>
operator+(typename __debug_iter<_Container, _Iter>::difference_type __n,
          const __debug_iter<_Container, _Iter>& __x)
{
    return __x + __n;
}

#endif  // _LIBCPP_DEBUG

#ifdef _LIBCPP_MOVE

template <class _C>
inline
auto
begin(_C& __c) -> decltype(__c.begin())
{
    return __c.begin();
}

template <class _C>
inline
auto
begin(const _C& __c) -> decltype(__c.begin())
{
    return __c.begin();
}

template <class _C>
inline
auto
end(_C& __c) -> decltype(__c.end())
{
    return __c.end();
}

template <class _C>
inline
auto
end(const _C& __c) -> decltype(__c.end())
{
    return __c.end();
}

#else

template <class _C>
inline
typename _C::iterator
begin(_C& __c)
{
    return __c.begin();
}

template <class _C>
inline
typename _C::const_iterator
begin(const _C& __c)
{
    return __c.begin();
}

template <class _C>
inline
typename _C::iterator
end(_C& __c)
{
    return __c.end();
}

template <class _C>
inline
typename _C::const_iterator
end(const _C& __c)
{
    return __c.end();
}

#endif

template <class _T, size_t _N>
inline
_T*
begin(_T (&__array)[_N])
{
    return __array;
}

template <class _T, size_t _N>
inline
_T*
end(_T (&__array)[_N])
{
    return __array + _N;
}

_LIBCPP_END_NAMESPACE_STD

#endif  // _LIBCPP_ITERATOR