#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
const long long inf = 1e18 + 5;
const long long MX = 303030;
int cox[4] = {1, -1, 0, 0};
int coy[4] = {0, 0, 1, -1};
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
long long leastbit(long long a) { return a & (-a); }
long long C(int a, int b) {
  long long res = 1;
  for (int i = 0; i < b; i++) res = res * (a - i) / (i + 1);
  return res;
}
long long powmod(long long a, long long b) {
  if (b == 0) return 1;
  long long cnt = powmod(a, b / 2);
  (cnt *= cnt) %= mod;
  if (b & 1) {
    (cnt *= a) %= mod;
  }
  return cnt;
}
int n, a[200005], b[200005], pos[200005], ans;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  long long a, b, n, l, ans, t, m, r, st, mid, right, left;
  cin >> a >> b >> n;
  while (n--) {
    cin >> st >> t >> m;
    ans = -1;
    l = st;
    r = 1000000000;
    while (l <= r) {
      mid = (l + r) >> 1;
      right = (mid - 1) * mid * b / 2;
      left = (st - 2) * (st - 1) * b / 2;
      if (right - left + (mid - st + 1) * a > t * m || t < a + (mid - 1) * b) {
        r = mid - 1;
      } else
        l = mid + 1, ans = mid;
    }
    cout << ans << endl;
  }
  return 0;
}
