#include <bits/stdc++.h>
using namespace std;
long long a, b, n, l, t, m;
bool f(int r) {
  long long x =
      (r - l + (long long)1) * (2 * a + b * (r + l - (long long)2)) / 2;
  if (a + b * (r - 1) > t) return false;
  return x <= m * t;
}
int main() {
  scanf("%I64d%I64d%I64d", &a, &b, &n);
  for (int i = 0; i < n; i++) {
    scanf("%d%d%d", &l, &t, &m);
    if (a + (l - 1) * b > t) {
      printf("-1\n");
      continue;
    }
    int low = l, high = 10000005;
    while (high - low > 1) {
      int mid = (high + low) / 2;
      if (!f(mid))
        high = mid;
      else
        low = mid;
    }
    if (f(high)) low = high;
    if (f(low))
      printf("%d\n", low);
    else
      printf("-1\n");
  }
  return 0;
}
