#include <bits/stdc++.h>
using namespace std;
struct _ {
  _() { ios_base::sync_with_stdio(0); }
} _;
template <class A, class B>
ostream &operator<<(ostream &o, pair<A, B> t) {
  o << "(" << t.first << ", " << t.second << ")";
  return o;
}
template <class T>
string tostring(T first, int len = 0, char c = '0') {
  stringstream ss;
  ss << first;
  string r = ss.str();
  if (r.length() < len) r = string(len - r.length(), c) + r;
  return r;
}
template <class T>
void PV(T a, T b, int n = 0, int w = 0, string s = " ") {
  int c = 0;
  while (a != b) {
    cout << tostring(*a++, w, ' ');
    if (a != b && (n == 0 || ++c % n))
      cout << s;
    else
      cout << "\n";
    cout.flush();
  }
}
template <class T>
inline bool chmin(T &a, T b) {
  return a > b ? a = b, 1 : 0;
}
template <class T>
inline bool chmax(T &a, T b) {
  return a < b ? a = b, 1 : 0;
}
const long long linf = 0x3f3f3f3f3f3f3f3fLL;
const int inf = 0x3f3f3f3f;
const int mod = int(1e9) + 7;
const int N = 111111;
long long A, B, n;
int main() {
  cin >> A >> B >> n;
  vector<int> res;
  while (n--) {
    long long l, t, m;
    cin >> l >> t >> m;
    if (A + (l - 1) * B > t) {
      res.push_back(-1);
      continue;
    }
    long long L = 1, R = 1000000;
    while (L < R) {
      long long M = (L + R + 1) / 2;
      long long a0 = A + (l - 1) * B;
      long long sum = a0 * M + (M - 1) * M * B / 2;
      if (sum > m * t || A + (l + M - 1 - 1) * B > t) {
        R = M - 1;
      } else {
        L = M;
      }
    }
    res.push_back(l + L - 1);
  }
  for (int i : res) cout << i << "\n";
  return 0;
}
