import java.util.ArrayList;
import java.util.Scanner;

class Main {
	public static void main(String[] args) {
		new Main().run();
	}
	
	long solve(long A,long B,long C) {
		if(C==1&&A>1)return -1;
		long ans=0;
		while(A>0) {
			if(C<=A&&A<=2*C-2) {
				A=0;
				ans+=B;
			}else if(A%C!=0) {
				A-=A%C;
			}else {
				A/=C;
			}
			ans+=B;
		}
		return ans;
	}
	
	void run() {
		Scanner sc=new Scanner(System.in);
		int Q=sc.nextInt();
		for(int q=0;q<Q;++q) {
			long A=sc.nextLong();
			long B=sc.nextLong();
			long C=sc.nextLong();
			System.out.println(solve(A,B,C));
		}
	}
}