#include <iostream>
using namespace std;
int main(){
	int Q;
	cin >> Q;
	for (int i = 0; i < Q; i++){
		int A, B, C;
		cin >> A >> B >> C;
		if (C == 1){
			cout << -1 << endl;
		} else {
			long long ans = 0;
			while (A > 0){
				if (C >= 3 && C < A && A <= C * 2 - 2){
					ans += B * 2;
					 break;
				}
				if (A % C != 0){
					ans += B;
					A -= A % C;
				}
				if (A == 0){
					break;
				}
				ans += B;
				A /= C;
			}
			cout << ans << endl;
		}
	}
}