Language: C++

#include <bits/stdc++.h>
using namespace std;
using ll=long long;

int main(){
  ll N,D,A;
  cin>>N>>D>>A;
  vector<pair<ll,ll>> xh(N);
  for(int i=0;i<N;i++){
    ll x,h;
    cin>>x>>h;
    xh.at(i)=make_pair(x,(h-1)/A+1);
  }
  
  sort(xh.begin(),xh.end());
  
  ll ans=0;
  vector<ll> sum(N+1,0);
  for(int i=0;i<N;i++){
    sum.at(i+1)+=sum.at(i);
    if(sum.at(i+1)<xh.at(i).second){
      ll tmp=xh.at(i).second-sum.at(i+1);
      ans+=tmp;
      int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      sum.at(i+1)+=tmp;
      sum.at(k+1)-=tmp;
    }
  }
  
  cout<<ans<<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:24:63: error: no match for 'operator+' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} and 'll' {aka 'long long int'})
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                       ~~~~~~~~^~~~
      |                                                            |    |
      |                                                            |    ll {aka long long int}
      |                                                            __gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type {aka std::pair<long long int, long long int>}
In file included from /usr/include/c++/14/bits/stl_algobase.h:67,
                 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/stl_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'll' {aka 'long long int'}
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'll' {aka 'long long int'}
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
In file included from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   mismatched types 'const _CharT*' and 'std::pair<long long int, long long int>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'll' {aka 'long long int'}
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   '__gnu_cxx::__alloc_traits<std::allocator<std::pair<long long int, long long int> >, std::pair<long long int, long long int> >::value_type' {aka 'std::pair<long long int, long long int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   24 |       int k=upper_bound(xh.begin(),xh.end(),make_pair(xh.at(i)+2*D,0));
      |                                                                  ^
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:24:66: note:   mismatched types 'const _Cha