#include <bits/stdc++.h>
using namespace std;
#define Foreach(i, c) for(__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define For(i,a,b) for(int (i)=(a);(i) < (b); ++(i))
#define rof(i,a,b) for(int (i)=(a);(i) > (b); --(i))
#define rep(i, c)  for(auto &(i) : (c))
#define x     first
#define y     second
#define pb  push_back
#define PB  pop_back()
#define iOS  ios_base::sync_with_stdio(false)
#define sqr(a)  (((a) * (a)))
#define all(a)  a.begin() , a.end()
#define error(x) cerr << #x << " = " << (x) <<endl
#define Error(a,b) cerr<<"( "<<#a<<" , "<<#b<<" ) = ( "<<(a)<<" , "<<(b)<<" )\n";
#define errop(a) cerr<<#a<<" = ( "<<((a).x)<<" , "<<((a).y)<<" )\n";
#define coud(a,b) cout<<fixed << setprecision((b)) << (a)
#define L(x)  ((x)<<1)
#define R(x)  (((x)<<1)+1)
#define umap  unordered_map
//#define max(x,y)  ((x) > (y) ? (x) : (y))
#define double long double
typedef long long ll;
typedef pair<int,int>pii;
typedef vector<int> vi;
typedef complex<double> point;
ll A,B,n,l,t,m,s;
inline ll comb(ll x){
	return (x * (x-1LL))/2LL;
}
inline ll h(ll i){
	return A + (i-1LL) * B;
}
inline bool check(ll r){
	ll e = comb(r) - comb(l-1LL);
	if(B && (double)e  > 2e18 / (double)B)
		return false;
	if(h(r) > t) return false;
	s = m * t;
	s -= e * B;
	s -= A * (r - l + 1LL);
	return (s >= 0LL);
}
int main(){
	iOS;
	cin >> A >> B >> n;
	while(n --){
		cin >> l >> t >> m;
		if(h(l) > t){
			cout << -1 << '\n';
			continue;
		}
		ll lo = l, hi = max(t, m) + l + 5;
		while(lo < hi){
			ll mid = (lo + hi)/2LL;
			if(check(mid))
				lo = mid;
			else
				hi = mid - 1LL;
			if(lo + 1LL == hi){
				if(check(hi))
					lo = hi;
				else
					hi = lo;
			}
		}
		cout << lo << '\n';
	}
}