#include <bits/stdc++.h>
using namespace std;
int main() {
  long long A, B;
  int N;
  long long l, r, t, tt, M;
  cin >> A >> B >> N;
  for (int i = 0; i < N; i++) {
    scanf("%I64d%I64d%I64d", &l, &t, &M);
    long long st = l, ed = l + 1000000;
    long long H = A + (l - 1) * B;
    long long D = B, C = t / B;
    if (t < H) {
      puts("-1");
      continue;
    }
    while (ed - st > 1) {
      long long md = (st + ed) >> 1;
      long long E = A + (md - 1) * B;
      long long L = md - l + 1;
      long long tot = (H + E) * L / 2;
      long long tt = max(E, (tot - 1 + M) / M);
      if (t >= tt)
        st = md;
      else
        ed = md;
    }
    long long E = A + (ed - 1) * B;
    long long L = ed - l + 1;
    long long tot = (H + E) * L / 2;
    long long tt = max(E, (tot - 1 + M) / M);
    if (t >= tt) st++;
    cout << st << endl;
  }
}
