#include<bits/stdc++.h>
using namespace std;
#define rep(i,x,y) for(int i=x;i<y;i++)
#define range(a) (a).begin(),(a).end()
#define print(A,n) rep(i,0,n){cout<<(i ? " ":"")<<A[i];}cout<<endl;
#define pprint(A,m,n) rep(j,0,m){print(A[j],n);}
const long mod=1e9+7;
const int size=1e5;
const int INF=1e9;
int main(){
	int Q;cin>>Q;
	long a,b,c;
	rep(i,0,Q){
		cin>>a>>b>>c;
		long res=0;
        if(c==1){
            cout<<-1<<endl;
            continue;
        }
		while(a>0){
			if(a<c){ res++; break; }
            else if(a<2*c-1){ res+=2; break; }
			else if(a%c==0) res++;
			else res+=2;
			a=a/c;
		}cout<<res*b<<endl;
	}
}