#include <bits/stdc++.h>
using namespace std;
long long sum(long long a, long long b, long long r) {
  if (r == 0) return 0;
  long long ret = a * r + b * (r - 1) * r / 2;
  return ret;
}
inline long long h(long long i, long long a, long long b) {
  return a + (i - 1LL) * b;
}
int main() {
  long long a, b, n;
  cin >> a >> b >> n;
  for (int i = 0; i < n; i++) {
    long long l, t, m;
    cin >> l >> t >> m;
    if (h(l, a, b) > t) {
      cout << -1 << endl;
      continue;
    }
    long long x = 1, y = 10000000;
    long long indx = -1;
    while (x <= y) {
      long long mid = (x + y) / 2ll;
      long long s = sum(a, b, mid) - sum(a, b, l - 1);
      if (s <= t * m && h(mid, a, b) <= t) {
        x = mid + 1;
        indx = mid;
      } else {
        y = mid - 1;
      }
    }
    cout << indx << endl;
  }
}
