#include <bits/stdc++.h>
using namespace std;
const int INF = 0x7fffffff;
const int N = 1e5 + 5;
inline long long read() {
  long long x = 0, rev = 0, ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') rev = 1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = (x << 1) + (x << 3) + ch - '0';
    ch = getchar();
  }
  return rev ? -x : x;
}
long long a, b, n;
bool judge(long long L, long long R, long long t, long long m) {
  if (a + (R - 1) * b <= t) {
    long long ret = a * (R - L + 1) + (R - L + 1) * (R + L - 2) / 2 * b;
    return ret <= t * m;
  }
  return 0;
}
int main() {
  a = read(), b = read(), n = read();
  while (n--) {
    long long l = read(), t = read(), m = read();
    long long L = l, R = (t - a) / b + 1;
    while (L < R) {
      long long mid = (L + R + 1) >> 1;
      if (judge(l, mid, t, m))
        L = mid;
      else
        R = mid - 1;
    }
    if (a + (L - 1) * b <= t)
      cout << L << endl;
    else
      cout << -1 << endl;
  }
  return 0;
}
