#include<map>
#include<set>
#include<cmath>
#include<queue>
#include<stack>
#include<vector>
#include<cstdio>
#include<cassert>
#include<iomanip>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define C 0.5772156649
#define pi acos(-1.0)
#define ll long long
#define mod 1000000007
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#pragma comment(linker, "/STACK:1024000000,1024000000")

using namespace std;

const double g=10.0,eps=1e-7;
const int N=2000000+10,maxn=1000000+10,inf=0x3f3f3f;

ll a,b;
bool ok(ll l,ll r,ll t,ll m)
{
    if(a+(r-1)*b<=t)
    {
        ll p=a*(r-l+1)+(l+r-2)*(r-l+1)/2*b;

        return p<=t*m;
    }
    return 0;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n;
    cin>>a>>b>>n;
    while(n--)
    {
        ll l,t,m;
        cin>>l>>t>>m;
        ll L=l,R=10*N;
        while(L<R-1)
        {
            ll mid=(L+R)/2;
          //  cout<<L<<" "<<mid<<" "<<R<<endl;
            if(ok(l,mid,t,m))L=mid;
            else R=mid;
        }
        if(a+(L-1)*b<=t)cout<<L<<endl;
        else cout<<-1<<endl;
    }
    return 0;
}
/********************
2 3 1
148990 913922 18257
********************/