_ForwardIter2 swap_ranges(_ForwardIter1 __first1, _ForwardIter1 __last1,
                          _ForwardIter2 __first2) {
  for ( ; __first1 != __last1; ++__first1, ++__first2)
    iter_swap(__first1, __first2);
  return __first2;
}

// transform
template <class _InputIter, class _OutputIter, class _UnaryOperation>
_OutputIter transform(_InputIter __first, _InputIter __last,
                      _OutputIter __result, _UnaryOperation __opr) {
  __stl_debug_check(__check_range(__first, __last));
  for ( ; __first != __last; ++__first, ++__result)
    *__result = __opr(*__first);
  return __result;
}

template <class _InputIter1, class _InputIter2, class _OutputIter,
          class _BinaryOperation>
_OutputIter transform(_InputIter1 __first1, _InputIter1 __last1,
                      _InputIter2 __first2, _OutputIter __result,
                      _BinaryOperation __binary_op) {
  for ( ; __first1 != __last1; ++__first1, ++__first2, ++__result)
    *__result = __binary_op(*__first1, *__first2);
  return __result;
}


// replace, replace_if, replace_copy, replace_copy_if
template <class _ForwardIter, class _Tp>
void replace(_ForwardIter __first, _ForwardIter __last,
             const _Tp& __old_value, const _Tp& __new_value) {
  for ( ; __first != __last; ++__first)
    if (*__first == __old_value)
      *__first = __new_value;
}

template <class _ForwardIter, class _Predicate, class _Tp>
void replace_if(_ForwardIter __first, _ForwardIter __last,
                _Predicate __pred, const _Tp& __new_value) {
  for ( ; __first != __last; ++__first)
    if (__pred(*__first))
      *__first = __new_value;
}

template <class _InputIter, class _OutputIter, class _Tp>
_OutputIter replace_copy(_InputIter __first, _InputIter __last,
                         _OutputIter __result,
                         const _Tp& __old_value, const _Tp& __new_value) {
  for ( ; __first != __last; ++__first, ++__result)
    *__result = *__first == __old_value ? __new_value : *__first;
  return __result;
}

template <class Iterator, class _OutputIter, class _Predicate, class _Tp>
_OutputIter replace_copy_if(Iterator __first, Iterator __last,
                            _OutputIter __result,
                            _Predicate __pred, const _Tp& __new_value) {
  for ( ; __first != __last; ++__first, ++__result)
    *__result = __pred(*__first) ? __new_value : *__first;
  return __result;
}

// generate and generate_n
template <class _ForwardIter, class _Generator>
void generate(_ForwardIter __first, _ForwardIter __last, _Generator __gen) {
  for ( ; __first != __last; ++__first)
    *__first = __gen();
}

template <class _OutputIter, class _Size, class _Generator>
_OutputIter generate_n(_OutputIter __first, _Size __n, _Generator __gen) {
  for ( ; __n > 0; --__n, ++__first)
    *__first = __gen();
  return __first;
}

// remove, remove_if, remove_copy, remove_copy_if

template <class _InputIter, class _OutputIter, class _Tp>
_OutputIter remove_copy(_InputIter __first, _InputIter __last,
                        _OutputIter __result, const _Tp& __value) {
  for ( ; __first != __last; ++__first)
    if (*__first != __value) {
      *__result = *__first;
      ++__result;
    }
  return __result;
}

template <class _InputIter, class _OutputIter, class _Predicate>
_OutputIter remove_copy_if(_InputIter __first, _InputIter __last,
                           _OutputIter __result, _Predicate __pred) {
  for ( ; __first != __last; ++__first)
    if (!__pred(*__first)) {
      *__result = *__first;
      ++__result;
    }
  return __result;
}

template <class _ForwardIter, class _Tp>
_ForwardIter remove(_ForwardIter __first, _ForwardIter __last,
		       const _Tp& __value) {
  __stl_debug_check(__check_range(__first, __last));
  __first = find(__first, __last, __value);
  if (__first == __last)
    return __first;
  else { 
    _ForwardIter __next = __first;
    return remove_copy(++__next, __last, __first, __value);
  }
}

template <class _ForwardIter, class _Predicate>
_ForwardIter remove_if(_ForwardIter __first, _ForwardIter __last,
			  _Predicate __pred) {
  __stl_debug_check(__check_range(__first, __last));
  __first = find_if(__first, __last, __pred);
  if ( __first == __last )
    return __first;
  else {
    _ForwardIter __next = __first;
    return remove_copy_if(++__next, __last, __first, __pred);
  }
}

// unique and unique_copy

template <class _InputIter, class _OutputIter, class _Tp>
_OutputIter __unique_copy(_InputIter __first, _InputIter __last,
                          _OutputIter __result, _Tp*) {
  _Tp __value = *__first;
  *__result = __value;
  while (++__first != __last)
    if (__value != *__first) {
      __value = *__first;
      *++__result = __value;
    }
  return ++__result;
}

template <class _InputIter, class _ForwardIter>
_ForwardIter __unique_copy(_InputIter __first, _InputIter __last,
                           _ForwardIter __result, forward_iterator_tag) {
  *__result = *__first;
  while (++__first != __last)
    if (*__result != *__first) *++__result = *__first;
  return ++__result;
}

template <class InputIterator, class OutputIterator, class BinaryPredicate,
					    class _Tp>
OutputIterator __unique_copy(InputIterator first, InputIterator last,
                             OutputIterator result,
                             BinaryPredicate binary_pred, _Tp*) {
  _Tp value = *first;
  *result = value;
  while (++first != last)
    if (!binary_pred(value, *first)) {
      value = *first;
      *++result = value;
    }
  return ++result;
}

template <class _InputIter, class _ForwardIter, class _BinaryPredicate>
_ForwardIter __unique_copy(_InputIter __first, _InputIter __last,
                           _ForwardIter __result, 
                           _BinaryPredicate __binary_pred,
                           forward_iterator_tag) {
  *__result = *__first;
  while (++__first != __last)
    if (!__binary_pred(*__result, *__first)) *++__result = *__first;
  return ++__result;
}

// rotate and rotate_copy, and their auxiliary functions

template <class _ForwardIter, class _Distance>
_ForwardIter __rotate(_ForwardIter __first,
                      _ForwardIter __middle,
                      _ForwardIter __last,
                      _Distance*,
                      forward_iterator_tag) {
  if (__first == __middle)
    return __last;
  if (__last  == __middle)
    return __first;

  _ForwardIter __first2 = __middle;
  do {
    swap(*__first++, *__first2++);
    if (__first == __middle)
      __middle = __first2;
  } while (__first2 != __last);

  _ForwardIter __new_middle = __first;

  __first2 = __middle;

  while (__first2 != __last) {
    swap (*__first++, *__first2++);
    if (__first == __middle)
      __middle = __first2;
    else if (__first2 == __last)
      __first2 = __middle;
  }

  return __new_middle;
}

template <class _BidirectionalIter, class _Distance>
_BidirectionalIter __rotate(_BidirectionalIter __first,
                            _BidirectionalIter __middle,
                            _BidirectionalIter __last,
                            _Distance*,
                            bidirectional_iterator_tag) {
  if (__first == __middle)
    return __last;
  if (__last  == __middle)
    return __first;

  __reverse(__first,  __middle, bidirectional_iterator_tag());
  __reverse(__middle, __last,   bidirectional_iterator_tag());

  while (__first != __middle && __middle != __last)
    swap (*__first++, *--__last);

  if (__first == __middle) {
    __reverse(__middle, __last,   bidirectional_iterator_tag());
    return __last;
  }
  else {
    __reverse(__first,  __middle, bidirectional_iterator_tag());
    return __first;
  }
}

template <class _RandomAccessIter, class _Distance, class _Tp>
_RandomAccessIter __rotate(_RandomAccessIter __first,
                           _RandomAccessIter __middle,
                           _RandomAccessIter __last,
                           _Distance *, _Tp *) {

  _Distance __n = __last   - __first;
  _Distance __k = __middle - __first;
  _Distance __l = __n - __k;
  _RandomAccessIter __result = __first + (__last - __middle);

  if (__k==0)  /* __first == middle */
    return __last;

  if (__k == __l) {
    swap_ranges(__first, __middle, __middle);
    return __result;
  }

  _Distance __d = __gcd(__n, __k);

  for (_Distance __i = 0; __i < __d; __i++) {
    _Tp __tmp = *__first;
    _RandomAccessIter __p = __first;

    if (__k < __l) {
      for (_Distance __j = 0; __j < __l/__d; __j++) {
	if (__p > __first + __l) {
          *__p = *(__p - __l);
          __p -= __l;
        }

        *__p = *(__p + __k);
        __p += __k;
      }
    }

    else {
      for (_Distance __j = 0; __j < __k/__d - 1; __j ++) {
        if (__p < __last - __k) {
          *__p = *(__p + __k);
          __p += __k;
        }

        *__p = * (__p - __l);
        __p -= __l;
      }
    }

    *__p = __tmp;
    ++__first;
  }

  return __result;
}

// Return a random number in the range [0, __n).  This function encapsulates
// whether we're using rand (part of the standard C library) or lrand48
// (not standard, but a much better choice whenever it's available).

template <class _Distance>
inline _Distance __random_number(_Distance __n) {
#ifdef __STL_NO_DRAND48
  return rand() % __n;
#else
  return lrand48() % __n;
#endif
}

template <class _RandomAccessIter>
void random_shuffle(_RandomAccessIter __first,
		    _RandomAccessIter __last) {
  __stl_debug_check(__check_range(__first, __last));
  if (__first == __last) return;
  for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
    iter_swap(__i, __first + __random_number((__i - __first) + 1));
}

template <class _RandomAccessIter, class _RandomNumberGenerator>
void random_shuffle(_RandomAccessIter __first, _RandomAccessIter __last,
                    _RandomNumberGenerator& __rand) {
  __stl_debug_check(__check_range(__first, __last));
  if (__first == __last) return;
  for (_RandomAccessIter __i = __first + 1; __i != __last; ++__i)
    iter_swap(__i, __first + __rand((__i - __first) + 1));
}

// random_sample and random_sample_n (extensions, not part of the standard).

template <class _ForwardIter, class _OutputIter, class _Distance>
_OutputIter random_sample_n(_ForwardIter __first, _ForwardIter __last,
                            _OutputIter __out, const _Distance __n)
{
  _Distance __remaining = 0;
  distance(__first, __last, __remaining);
  _Distance __m = min(__n, __remaining);

  while (__m > 0) {
    if (__random_number(__remaining) < __m) {
      *__out = *__first;
      ++__out;
      --__m;
    }

    --__remaining;
    ++__first;
  }
  return __out;
}


template <class _ForwardIter, class _OutputIter, class _Distance,
          class _RandomNumberGenerator>
_OutputIter random_sample_n(_ForwardIter __first, _ForwardIter __last,
                            _OutputIter __out, const _Distance __n,
                            _RandomNumberGenerator& __rand)
{
  _Distance __remaining = 0;
  distance(__first, __last, __remaining);
  _Distance __m = min(__n, __remaining);

  while (__m > 0) {
    if (__rand(__remaining) < __m) {
      *__out = *__first;
      ++__out;
      --__m;
    }

    --__remaining;
    ++__first;
  }
  return __out;
}

template <class _InputIter, class _RandomAccessIter, class _Distance>
_RandomAccessIter __random_sample(_InputIter __first, _InputIter __last,
                                  _RandomAccessIter __out,
                                  const _Distance __n)
{
  _Distance __m = 0;
  _Distance __t = __n;
  for ( ; __first != __last && __m < __n; ++__m, ++__first) 
    __out[__m] = *__first;

  while (__first != __last) {
    ++__t;
    _Distance __M = __random_number(__t);
    if (__M < __n)
      __out[__M] = *__first;
    ++__first;
  }

  return __out + __m;
}

template <class _InputIter, class _RandomAccessIter,
          class _RandomNumberGenerator, class _Distance>