#include<bits/stdc++.h>
#define REP(i,n) for(int i=0,i##_len=(n);i<i##_len;++i)
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define All(x) (x).begin(),(x).end()
using namespace std;
typedef long long ll;

int main(){
    int Q;cin>>Q;
    REP(q,Q){
        ll A,B,C;cin>>A>>B>>C;
        if(C==1){
            cout<<-1<<endl;
            continue;
        }
        ll ans=0;
        while(A>2*C-2){
            if(A%C==0){
                A/=C;
                ans+=B;
            }
            else{
                A-=A%C;
                ans+=B;
            }
        }
        if(0<A&&A<C) ans+=B;
        if(C<=A) ans+=2*B;
        cout<<ans<<endl;
    }
}