#include <iostream>
#include <fstream>

#define IN "a.in"
#define OUT "a.out"

//#define fin cin
//#define fout cout

using namespace std;

ifstream fin ( IN ) ;
ofstream fout ( OUT ) ;

int main()
{
    long long a , b , n ;
    fin >> a >> b >> n ;
    for ( register int i = 1 ; i <= n ; ++ i ){
        long long l , t , m ;
        fin >> l >> t >> m ;
        long long st = 1 ;
        long long dr = 2000000 ;
        long long ans = -1 ;
        while ( st <= dr ) {
            long long mij = ( st + dr ) / 2 ;
            long long lb = l ;
            long long ub = mij ;
            if ( a + ( mij - 1 ) * b <= t and ( ub - lb + 1 ) * a + ( ( ( ub - 1 ) * ub ) / 2 - ( ( lb - 1 ) * ( lb - 2 ) ) / 2 ) * b <= m * t ){
                ans = mij ;
                st = mij + 1 ;
            }
            else dr = mij - 1 ;
        }
        fout << ans << '\n' ;
    }
    return 0;
}