#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-7;
const int MOD = (int)1e9 + 7;
const int MAXN = (int)1e5 + 10;
long long A, B, n;
long long solve(long long l, long long m, long long k) {
  long long ans = A + (l + k - 1) * B;
  long long val = (k + 1) * (A + (l - 1) * B) + k * (k + 1) * B / 2;
  ans = max(ans, (val + m - 1) / m);
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> A >> B >> n;
  for (int i = 0; i < n; ++i) {
    long long l, t, m;
    cin >> l >> t >> m;
    if (solve(l, m, 0) > t) {
      cout << -1 << endl;
      continue;
    }
    long long lo = 0, hi = 1;
    while (solve(l, m, hi) <= t) hi *= 2;
    while (lo + 1 < hi) {
      int mid = (lo + hi) >> 1;
      if (solve(l, m, mid) <= t)
        lo = mid;
      else
        hi = mid;
    }
    cout << l + lo << endl;
  }
  return 0;
}
