#include <bits/stdc++.h>
using namespace std;
using namespace std::chrono;
long long power(long long x, unsigned long long y) {
  long long res = 1;
  while (y > 0) {
    if (y & 1) {
      res = res * x;
    }
    y = y >> 1;
    x = x * x;
  }
  return res;
}
long long powermod(long long x, unsigned long long y, long long p) {
  long long res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) {
      res = (res * x) % p;
    }
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long min(long long a, long long b) { return a < b ? a : b; }
long long max(long long a, long long b) { return a > b ? a : b; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  long long f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
void snow() {
  long long a, b, n;
  cin >> a >> b >> n;
  while (n--) {
    long long l, t, m;
    cin >> l >> t >> m;
    l--;
    long long ans = l;
    long long r = 1e9;
    long long faci = m * t;
    if (t < (a + l * (b))) {
      cout << -1 << '\n';
      continue;
    }
    long long start = a + l * (b);
    long long ll = l;
    while (l <= r) {
      long long mid = (l + r) / 2;
      long long height = a + mid * (b);
      long long sum =
          start * (mid - ll + 1) + b * ((mid - ll) * (mid - ll + 1)) / 2;
      if (height <= t && sum <= m * t) {
        ans = mid;
        l = mid + 1;
      } else {
        r = mid - 1;
      }
    }
    cout << ans + 1 << '\n';
  }
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long t;
  t = 1;
  while (t--) snow();
  return 0;
}
