#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
ll mod=1e9+7;

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