Creating Multiples

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

const int MAX = 200005;

int a[MAX];

int main() {
  cin.tie(0)->sync_with_stdio(0);

  int b, l;
  cin >> b >> l;

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

  if (v == 0) {
    cout << "0 0\n";
    exit(0);
  }

  for (int i = 1; i <= l; ++i) {
    if (i & 1) {
      v -= a[i];
      if (v < 0) v += b+1;
      int rem = b+1-v;
      if (rem == b+1) rem = 0;
      if (rem < a[i]) {
        cout << i << ' ' << rem << '\n';
        exit(0);
      }
      v += a[i];
      if (v >= b+1) v -= b+1;
    } else {
      v += a[i];
      if (v >= b+1) v -= b+1;
      // cout << "Teste 2: " << v << ' ' << a[i] << '\n';
      if (v < a[i]) {
        cout << i << ' ' << v << '\n';
        exit(0);
      }
      v -= a[i];
      if (v < 0) v += b+1;
    }
  }

  cout << "-1 -1\n";
}