#include <iostream>
using namespace std;
long long get(long long a, long long b, long long x, long long y)
{
	x--;
	y--;
	long long sum = (y * (y - 1) - x * (x - 1)) / 2;
	return a * (y - x) + sum * b;
}
int main()
{
	ios::sync_with_stdio(false);
	long long a, b, q;
	cin >> a >> b >> q;
	while (q--)
	{
		long long l, t, m;
		cin >> l >> t >> m;
		long long ll = l, rr = 2e6 + 5;
		while (rr - ll > 1)
		{
			long long mid = (ll + rr) / 2;
			if (a + (mid - 2) * b <= t && get(a, b, l, mid) <= t * m)
				ll = mid;
			else
				rr = mid;
		}
		if (ll == l)
			ll = 0;
		cout << ll - 1 << '\n';
	}
	return 0;
}