Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef struct node
{
	int a,b;
	bool operator < (const node &A, const node &B)
	{
		return A.a < B.a;
	}
}NODE,*PNODE;
NODE shop[100001];
int main()
{
	int i,n,m,sum=0;
	scanf("%d %d",&n,&m);
	for(i=0;i<n;i++)
	{
		scanf("%d %d",&shop[i].a,&shop[i].b);
	}
	sort(shop,shop+n);
	for(i=0;i<n;i++)
	{
		if(shop[i].b>=m)
		{
			sum+=m*shop[i].a;
			break;
		}
		else
		{
			m-=shop[i].b;
			sum+=shop[i].a*shop[i].b;
		}
	}
	printf("%d",sum);
	return 0;
}

Compiler output:
a.cc:6:14: error: 'bool node::operator<(const node&, const node&)' must have exactly one argument
    6 |         bool operator < (const node &A, const node &B)
      |              ^~~~~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:71,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'constexpr bool __gnu_cxx::__ops::_Iter_less_iter::operator()(_Iterator1, _Iterator2) const [with _Iterator1 = node*; _Iterator2 = node*]':
/usr/include/c++/14/bits/stl_algo.h:1777:14:   required from 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1777 |           if (__comp(__i, __first))
      |               ~~~~~~^~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1817:25:   required from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1817 |           std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1908:31:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1908 |           std::__final_insertion_sort(__first, __last, __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4772:18:   required from 'void std::sort(_RAIter, _RAIter) [with _RAIter = node*]'
 4772 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_less_iter());
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:20:6:   required from here
   20 |         sort(shop,shop+n);
      |         ~~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:45:23: error: no match for 'operator<' (operand types are 'node' and 'node')
   45 |       { return *__it1 < *__it2; }
      |                ~~~~~~~^~~~~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:1241:5: note: candidate: 'template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator<(const __normal_iterator<_IteratorL, _Container>&, const __normal_iterator<_IteratorR, _Container>&)'
 1241 |     operator<(const __normal_iterator<_IteratorL, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1241:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:45:23: note:   'node' is not derived from 'const __gnu_cxx::__normal_iterator<_IteratorL, _Container>'
   45 |       { return *__it1 < *__it2; }
      |                ~~~~~~~^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1249:5: note: candidate: 'template<class _Iterator, class _Container> bool __gnu_cxx::operator<(const __normal_iterator<_Iterator, _Container>&, const __normal_iterator<_Iterator, _Container>&)'
 1249 |     operator<(const __normal_iterator<_Iterator, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1249:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:45:23: note:   'node' is not derived from 'const __gnu_cxx::__normal_iterator<_Iterator, _Container>'
   45 |       { return *__it1 < *__it2; }
      |                ~~~~~~~^~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Val_less_iter::operator()(_Value&, _Iterator) const [with _Value = node; _Iterator = node*]':
/usr/include/c++/14/bits/stl_algo.h:1757:20:   required from 'void std::__unguarded_linear_insert(_RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Val_less_iter]'
 1757 |       while (__comp(__val, __next))
      |              ~~~~~~^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1785:36:   required from 'void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1785 |             std::__unguarded_linear_insert(__i,
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
 1786 |                                 __gnu_cxx::__ops::__val_comp_iter(__comp));
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1817:25:   required from 'void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1817 |           std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1908:31:   required from 'void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1908 |           std::__final_insertion_sort(__first, __last, __comp);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:4772:18:   required from 'void std::sort(_RAIter, _RAIter) [with _RAIter = node*]'
 4772 |       std::__sort(__first, __last, __gnu_cxx::__ops::__iter_less_iter());
      |       ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:20:6:   required from here
   20 |         sort(shop,shop+n);
      |         ~~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/predefined_ops.h:98:22: error: no match for 'operator<' (operand types are 'node' and 'node')
   98 |       { return __val < *__it; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1241:5: note: candidate: 'template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator<(const __normal_iterator<_IteratorL, _Container>&, const __normal_iterator<_IteratorR, _Container>&)'
 1241 |     operator<(const __normal_iterator<_IteratorL, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1241:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:98:22: note:   'node' is not derived from 'const __gnu_cxx::__normal_iterator<_IteratorL, _Container>'
   98 |       { return __val < *__it; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1249:5: note: candidate: 'template<class _Iterator, class _Container> bool __gnu_cxx::operator<(const __normal_iterator<_Iterator, _Container>&, const __normal_iterator<_Iterator, _Container>&)'
 1249 |     operator<(const __normal_iterator<_Iterator, _Container>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1249:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/predefined_ops.h:98:22: note:   'node' is not derived from 'const __gnu_cxx::__normal_iterator<_Iterator, _Container>'
   98 |       { return __val < *__it; }
      |                ~~~~~~^~~~~~~
/usr/include/c++/14/bits/predefined_ops.h: In instantiation of 'bool __gnu_cxx::__ops::_Iter_less_val::operator()(_Iterator, _Value&) const [with _Iterator = node*; _Value = node]':
/usr/include/c++/14/bits/stl_heap.h:140:48:   required from 'void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare&) [with _RandomAccessIterator = node*; _Distance = long int; _Tp = node; _Compare = __gnu_cxx::__ops::_Iter_less_val]'
  140 |       while (__holeIndex > __topIndex && __comp(__first + __parent, __value))
      |                                          ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:247:23:   required from 'void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = node*; _Distance = long int; _Tp = node; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
  247 |       std::__push_heap(__first, __holeIndex, __topIndex,
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  248 |                        _GLIBCXX_MOVE(__value), __cmp);
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_heap.h:356:22:   required from 'void std::__make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare&) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
  356 |           std::__adjust_heap(__first, __parent, __len, _GLIBCXX_MOVE(__value),
      |           ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  357 |                              __comp);
      |                              ~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1593:23:   required from 'void std::__heap_select(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1593 |       std::__make_heap(__first, __middle, __comp);
      |       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1868:25:   required from 'void std::__partial_sort(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = node*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1868 |       std::__heap_select(__first, __middle, __last, __comp);
      |       ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1884:27:   required from 'void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = node*; _Size = long int; _Compare = __gnu_cxx::__ops::_Iter_less_iter]'
 1884 |               std::__partial_sort(__first, __last, __last, __comp);
      |               ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algo.h:1905:25:   required from 'void std::__