Language: C++

#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <string>
#include <cstring>
#include <map>
using namespace std;

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);

  int n;
  cin >> n;

  vector<int64_t> a(n), b(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < n; i++) {
    cin >> b[i];
  }

  vector<int64_t> differences(n);
  for (int i = 0; i < n; i++) {
    differences[i] = a[i] - b[i];
  }
  sort(differences.begin(), differences.end());

  set<int> changed_indices;

  int target = n - 1;
  for (int i = 0; i < n; i++) {
    while (target > i and differences[i] < 0) {
      changed_indices.insert(i);
      int supply = max(0LL, min(-differences[i], differences[target]));

      differences[i] += supply;
      differences[target] -= supply;

      if (supply > 0) {
        changed_indices.insert(target);
      }

      if (differences[target] <= 0) {
        target--;
      }
    }

    if (differences[i] < 0) {
      cout << -1 << endl;
      return 0;
    }
  }
  cout << changed_indices.size() << endl;

  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:37:23: error: no matching function for call to 'max(long long int, const long int&)'
   37 |       int supply = max(0LL, min(-differences[i], differences[target]));
      |                    ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:37:23: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'long int')
   37 |       int supply = max(0LL, min(-differences[i], differences[target]));
      |                    ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:37:23: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   37 |       int supply = max(0LL, min(-differences[i], differences[target]));
      |                    ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~