#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>

using namespace std;

#define int long long
#define endl "\n"

const long long INF = (long long)1e18;
const long long MOD = 1'000'000'007; 

string yn(bool f){return f?"Yes":"No";}
string YN(bool f){return f?"YES":"NO";}



signed main(){
	// cin.tie(nullptr);
	// ios::sync_with_stdio(false);
	// cout<<fixed<<setprecision(10);
	
	int Q;
	
	cin>>Q;
	
	for(int i = 0; i < Q; i++){
		int A, B, C;
		int a = 0, b = 0;
		int con = 0;
		vector<int> temp;
		bool f = true;
		
		cin>>A>>B>>C;
		
		if(C == 1){
			cout<<-1<<endl;
			continue;
		}
		
		while(A){
			if(A%C){
				con++;
			}
			temp.push_back(A%C);
			A /= C;
			con++;
		}

		con--;
		
		if(temp.size() >= 2){
			if(temp.back()*C + temp[temp.size()-2] <= (C-1)*2 && temp[temp.size()-2]){
				con--;
				// cout<<"<> "<<endl;
			}
		}
		
		cout<<con*B<<endl;
	}
	
	
	return 0;
}