Language: C++

using namespace std;
#include<bits/stdc++.h>
#define BEGIN ios_base::sync_with_stdio(0);cin.tie(0)
#define END return EXIT_SUCCESS
#define FOR(I,A,B) for((I)=(A);(I)<(B);(I)++)
#define REP(I,N) FOR(I,0,N)
#define UP(I,A,B) for((I)=(A);(I)<=(B);(I)++)
#define DW(I,A,B) for((I)=(A);(I)>=(B);(I)--)
#define IN(P) cin>>(P)
#define IN2(P1,P2) cin>>(P1)>>(P2)
#define IN3(P1,P2,P3) cin>>(P1)>>(P2)>>(P3)
#define INS(I,N,V) REP(I,N) cin>>V[I]
#define INS2(I,N,V1,V2) REP(I,N) cin>>V1[I]>>V2[I];
#define INS3(I,N,V1,V2,V3) REP(I,N) cin>>V1[I]>>V2[I]>>V3[I];
#define OUT(P) cout<<P<<endl
#define OUT2(P1,P2) cout<<P1<<" "<<P2<<endl
#define OUT3(P1,P2,P3) cout<<P1<<" "<<P2<<" "<<P3<<endl
#define OUTS(I,N,V) REP(I,N) cout<<V[i]<<endl
#define ALL(C) (C).begin(),(C).end()
#define RALL(C) (C).rbegin(),(C).rend()
#define mp make_pair
#define pb push_back
typedef unsigned long ul;
typedef unsigned int ui;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int N,K,i,j,a,b,cnt;
map<int,int> v;
vector<pair<int,int> > vv;

inline void solve(){
  IN2(N,K);
  REP(i,N){
    IN2(a,b);
    v[a]+=b;
  }
  for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
    vv.pb(mp(it->first,it->second));
  }
  sort(ALL(vv));
  REP(i,N){
    cnt+=vv[i].second;
    if(K<cnt){
      OUT(vv[i].first);
      return;
    }
  }
}

int main(int argc,char**argv){
  BEGIN;
  solve();
  END;
}


Compiler output:
a.cc: In function 'void solve()':
a.cc:38:41: error: conversion from '_Rb_tree_iterator<pair<[...],int>>' to non-scalar type '_Rb_tree_iterator<pair<[...],long int>>' requested
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                  ~~~~~~~^~
a.cc:38:46: error: no match for 'operator!=' (operand types are 'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} and 'std::map<int, int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, int>, std::_Select1st<std::pair<const int, int> >, std::less<int>, std::allocator<std::pair<const int, int> > >::iterator'})
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                            ~~^~~~~~~~~
      |                                            |        |
      |                                            |        _Rb_tree_iterator<pair<[...],int>>
      |                                            _Rb_tree_iterator<pair<[...],long int>>
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:2:
/usr/include/c++/14/bits/regex.h:1132:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1132 |     operator!=(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1132:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:1212:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1212 |     operator!=(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1212:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:1305:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1305 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1305:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:1379:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1379 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1379:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, int>, std::_Select1st<std::pair<const int, int> >, std::less<int>, std::allocator<std::pair<const int, int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:1473:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1473 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1473:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:1547:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1547 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1547:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, int>, std::_Select1st<std::pair<const int, int> >, std::less<int>, std::allocator<std::pair<const int, int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:1647:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1647 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1647:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/regex.h:2213:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator!=(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2213 |     operator!=(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2213:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1052:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator!=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1052 |     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1052:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::pair<_T1, _T2>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:455:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  455 |     operator!=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:455:5: note:   template argument deduction/substitution failed:
a.cc:38:54: note:   'std::map<int, long int>::iterator' {aka 'std::_Rb_tree<int, std::pair<const int, long int>, std::_Select1st<std::pair<const int, long int> >, std::less<int>, std::allocator<std::pair<const int, long int> > >::iterator'} is not derived from 'const std::reverse_iterator<_Iterator>'
   38 |   for(map<int,long>::iterator it=v.begin();it!=v.end();it++){
      |                                                      ^
/usr/include/c++/14/bits/stl_iterator.h:500:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  500 |     operator!=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:500:5: note:   template argument deduction/subs