#include <bits/stdc++.h>
using namespace std;
int A, B, q;
long long l, t, m;
bool check(long long len) {
  long long ind_left = l;
  long long ind_righ = ind_left + len - 1;
  long long num_left = A + (ind_left - 1) * B;
  long long num_righ = A + (ind_righ - 1) * B;
  long long need_time;
  if (len > m)
    need_time = ((num_left + num_righ) * len / 2 + m - 1) / m;
  else
    need_time = num_righ;
  return need_time <= t && num_righ <= t;
}
void work() {
  scanf("%d %d %d", &A, &B, &q);
  while (q--) {
    scanf("%lld %lld %lld", &l, &t, &m);
    long long lpt = 0, rpt = 1e6;
    while (lpt < rpt) {
      long long mid = (lpt + rpt + 1) >> 1;
      if (check(mid)) {
        lpt = mid;
      } else {
        rpt = mid - 1;
      }
    }
    if (lpt == 0) {
      puts("-1");
    } else {
      printf("%lld\n", l + rpt - 1);
    }
  }
}
int main() {
  work();
  return 0;
}
