#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) { return (b ? gcd(b, a % b) : a); }
bool isPrime(long long n) {
  if (n == 1) return false;
  if (n == 2) return true;
  for (long long i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
long long power(long long x, unsigned long long y, long long p = 1000000007) {
  long long res = 1;
  x = x % p;
  if (x == 0) return 0;
  while (y > 0) {
    if (y & 1) {
      res = (res * x) % p;
    }
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long digit(long long n) {
  long long ans = 0;
  while (n) {
    ans++;
    n /= 10;
  }
  return ans;
}
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
vector<long long> sieve(long long n) {
  long long *arr = new long long[n + 1]();
  vector<long long> vect;
  for (long long i = 2; i <= n; i++)
    if (arr[i] == 0) {
      vect.push_back(i);
      for (long long j = 2 * i; j <= n; j += i) arr[j] = 1;
    }
  return vect;
}
long long l, t, m, a, b;
void solve() {
  cin >> a >> b;
  long long n;
  cin >> n;
  for (long long i = 0; i < n; i++) {
    cin >> l >> t >> m;
    long long L = l, R = 1e8;
    long long sl = a + b * (l - 1);
    if (sl > t) {
      cout << -1 << endl;
      continue;
    }
    while (L + 1 < R) {
      long long mid = (L + R) / 2;
      long long term = (mid - l) + 1;
      long long sum = (term * (2 * a + (l + mid - 2) * b)) / 2;
      if (sum > min(m, term) * t || a + (mid - 1) * b > t) {
        R = mid;
      } else {
        L = mid;
      }
    }
    cout << L << endl;
  }
}
int32_t main() {
  ios_base ::sync_with_stdio(false), cin.tie(NULL);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
