#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <iomanip>
#include <set>
#include <tuple>
#define mkp make_pair
#define mkt make_tuple
#define rep(i,n) for(int i = 0; i < (n); ++i)
using namespace std;
typedef long long ll;
const ll MOD=1e9+7;

const ll INF=1e18;

void solve(){
  ll A,B,C;
  cin>>A>>B>>C;

  if(C==1){
    cout<<-1<<endl;
    return;
  }

  ll ans=0;
  ll now=A;
  ll res=INF;
  while(now>0){
    if(res==INF&&now<=2*(C-1)){
      res=ans+2*B;
    }

    if(now%C==0) now/=C;
    else now-=now%C;
    ans+=B;
  }
  cout<<min(ans,res)<<endl;
}

int main(){
  int Q;
  cin>>Q;
  rep(i,Q) solve();

  return 0;
}