Language: C++

#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;

int main() {
	int n, k;
	cin >> n >> k;

	vector<vector<int>>a(n, vector<long long>(2, 0));

	for (int i = 0; i < n; i++) {
		cin >> a[i][0] >> a[i][1];
		if (i > 1 && a[i][0] == a[i - 1][0]) {
			a[i][1] += a[i - 1][1];
			a[i - 1][0] = 0;
		}
	}


	sort(a.begin(), a.end());
	int c = 0;
	int d = 0;

	while (k != 0) {
		if (a[c][0] > 0) {
			if (k - a[c][1] > 0) {
				k -= a[c][1];
				c++;
				d = 0;
			}
			else {
				if (a[c][0] > 0 && d != a[c][1]) {
					d++;
					k--;
				}
			}
		}
		else {
			c++;
		}

	}
	cout << a[c][0] << endl;

	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:56: error: no matching function for call to 'std::vector<std::vector<int> >::vector(int&, std::vector<long long int>)'
   11 |         vector<vector<int>>a(n, vector<long long>(2, 0));
      |                                                        ^
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_vector.h:707:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&) [with <template-parameter-2-2> = _InputIterator; _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >]'
  707 |         vector(_InputIterator __first, _InputIterator __last,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:707:9: note:   template argument deduction/substitution failed:
a.cc:11:56: note:   deduced conflicting types for parameter '_InputIterator' ('int' and 'std::vector<long long int>')
   11 |         vector<vector<int>>a(n, vector<long long>(2, 0));
      |                                                        ^
/usr/include/c++/14/bits/stl_vector.h:678:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::initializer_list<_Tp>, const allocator_type&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; allocator_type = std::allocator<std::vector<int> >]'
  678 |       vector(initializer_list<value_type> __l,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:678:43: note:   no known conversion for argument 1 from 'int' to 'std::initializer_list<std::vector<int> >'
  678 |       vector(initializer_list<value_type> __l,
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:659:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, std::__type_identity_t<_Alloc>&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; std::__type_identity_t<_Alloc> = std::allocator<std::vector<int> >]'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:659:23: note:   no known conversion for argument 1 from 'int' to 'std::vector<std::vector<int> >&&'
  659 |       vector(vector&& __rv, const __type_identity_t<allocator_type>& __m)
      |              ~~~~~~~~~^~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::false_type) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; allocator_type = std::allocator<std::vector<int> >; std::false_type = std::false_type]'
  640 |       vector(vector&& __rv, const allocator_type& __m, false_type)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:640:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:635:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&, const allocator_type&, std::true_type) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; allocator_type = std::allocator<std::vector<int> >; std::true_type = std::true_type]'
  635 |       vector(vector&& __rv, const allocator_type& __m, true_type) noexcept
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:635:7: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_vector.h:624:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&, std::__type_identity_t<_Alloc>&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; std::__type_identity_t<_Alloc> = std::allocator<std::vector<int> >]'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:624:28: note:   no known conversion for argument 1 from 'int' to 'const std::vector<std::vector<int> >&'
  624 |       vector(const vector& __x, const __type_identity_t<allocator_type>& __a)
      |              ~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>&&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >]'
  620 |       vector(vector&&) noexcept = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:620:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:601:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >]'
  601 |       vector(const vector& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:601:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:569:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const value_type&, const allocator_type&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; size_type = long unsigned int; value_type = std::vector<int>; allocator_type = std::allocator<std::vector<int> >]'
  569 |       vector(size_type __n, const value_type& __value,
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:569:47: note:   no known conversion for argument 2 from 'std::vector<long long int>' to 'const std::vector<std::vector<int> >::value_type&' {aka 'const std::vector<int>&'}
  569 |       vector(size_type __n, const value_type& __value,
      |                             ~~~~~~~~~~~~~~~~~~^~~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(size_type, const allocator_type&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; size_type = long unsigned int; allocator_type = std::allocator<std::vector<int> >]'
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:556:51: note:   no known conversion for argument 2 from 'std::vector<long long int>' to 'const std::vector<std::vector<int> >::allocator_type&' {aka 'const std::allocator<std::vector<int> >&'}
  556 |       vector(size_type __n, const allocator_type& __a = allocator_type())
      |                             ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector(const allocator_type&) [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >; allocator_type = std::allocator<std::vector<int> >]'
  542 |       vector(const allocator_type& __a) _GLIBCXX_NOEXCEPT
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:542:7: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_vector.h:531:7: note: candidate: 'std::vector<_Tp, _Alloc>::vector() [with _Tp = std::vector<int>; _Alloc = std::allocator<std::vector<int> >]'
  531 |       vector() = default;
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:531:7: note:   candidate expects 0 arguments, 2 provided