#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100000 + 10;
long long A, B, N;
long long l, t, m;
int main() {
  cin >> A >> B >> N;
  for (int i = 1; i <= N; i++) {
    cin >> l >> t >> m;
    if (t < A + (l - 1) * B) {
      cout << -1 << endl;
      continue;
    }
    long long L = 1, R = 10000000, M;
    while (L <= R) {
      M = (L + R) / 2;
      if ((2 * A + (l + M - 2) * B) * (M - l + 1) > t * m * 2)
        R = M - 1;
      else
        L = M + 1;
    }
    cout << min(R, (t - A + B) / B) << endl;
  }
  return 0;
}
