Language: C++

#include<bits/stdc++.h>
using namespace std;
#define ll long long
ll n,k;
ll a,b;
vector<pair<ll,ll> > num;
vector<pair<ll,ll> > ::iterator iter;
int main(){
	
    cin>>n>>k;
    for(int i=1;i<=n;i++)  
    {
	    cin>>a>>b;
	   num.insert(make_pair(a,b));
	}
  ll sum=0;
  for(iter=num.begin();iter!=num.end();iter++)
      {
      	 sum+=iter->second;
      	 if(sum>=k)
      	   return 0*printf("%d\n",iter->first);
      }
  
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:14:22: error: no matching function for call to 'std::vector<std::pair<long long int, long long int> >::insert(std::pair<long long int, long long int>)'
   14 |            num.insert(make_pair(a,b));
      |            ~~~~~~~~~~^~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:1484:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, _InputIterator, _InputIterator) [with <template-parameter-2-2> = _InputIterator; _Tp = std::pair<long long int, long long int>; _Alloc = std::allocator<std::pair<long long int, long long int> >]'
 1484 |         insert(const_iterator __position, _InputIterator __first,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1484:9: note:   candidate expects 3 arguments, 1 provided
In file included from /usr/include/c++/14/vector:72:
/usr/include/c++/14/bits/vector.tcc:133:5: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, const value_type&) [with _Tp = std::pair<long long int, long long int>; _Alloc = std::allocator<std::pair<long long int, long long int> >; iterator = std::vector<std::pair<long long int, long long int> >::iterator; const_iterator = std::vector<std::pair<long long int, long long int> >::const_iterator; value_type = std::pair<long long int, long long int>]'
  133 |     vector<_Tp, _Alloc>::
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:133:5: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_vector.h:1395:7: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, value_type&&) [with _Tp = std::pair<long long int, long long int>; _Alloc = std::allocator<std::pair<long long int, long long int> >; iterator = std::vector<std::pair<long long int, long long int> >::iterator; const_iterator = std::vector<std::pair<long long int, long long int> >::const_iterator; value_type = std::pair<long long int, long long int>]'
 1395 |       insert(const_iterator __position, value_type&& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1395:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_vector.h:1413:7: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, std::initializer_list<_Tp>) [with _Tp = std::pair<long long int, long long int>; _Alloc = std::allocator<std::pair<long long int, long long int> >; iterator = std::vector<std::pair<long long int, long long int> >::iterator; const_iterator = std::vector<std::pair<long long int, long long int> >::const_iterator]'
 1413 |       insert(const_iterator __position, initializer_list<value_type> __l)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1413:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_vector.h:1439:7: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, size_type, const value_type&) [with _Tp = std::pair<long long int, long long int>; _Alloc = std::allocator<std::pair<long long int, long long int> >; iterator = std::vector<std::pair<long long int, long long int> >::iterator; const_iterator = std::vector<std::pair<long long int, long long int> >::const_iterator; size_type = long unsigned int; value_type = std::pair<long long int, long long int>]'
 1439 |       insert(const_iterator __position, size_type __n, const value_type& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1439:7: note:   candidate expects 3 arguments, 1 provided