#include "bits/stdc++.h"

#define MOD 1000000007
#define rep(i, n) for(ll i=0; i < (n); i++)
#define rrep(i, n) for(ll i=(n)-1; i >=0; i--)
#define ALL(v) v.begin(),v.end()
#define rALL(v) v.rbegin(),v.rend()
#define FOR(i, j, k) for(ll i=j;i<k;i++)
#define debug_print(var) cerr << #var << "=" << var <<endl;
#define DUMP(i, v)for(ll i=0;i<v.size();i++)cerr<<v[i]<<" "
#define fi first
#define se second

using namespace std;
typedef long long int ll;
typedef vector<ll> llvec;
typedef vector<double> dvec;
typedef pair<ll, ll> P;
typedef long double ld;
struct edge{ll x, c;};

ll A, B, C;

/**************************************
** A main function starts from here  **
***************************************/
int main(){
  ll Q;
  cin >> Q;
  while(Q--){
    cin >> A >> B >> C;

    ll ans = 0;
    if(C==1){
      ans =  -1;
      A = 0;
    }

    while(A>0){
      if(A<C){
        A=0;
        ans += B;
      }else if(A<=2*(C-1)){
        A = 0;
        ans += 2*B;
      }else{
        if(A%C!=0){
          A/=C;
          ans += 2*B;
        }else{
          A/=C;
          ans += B;
        }
      }
      //cerr << A << " "<<ans << endl;
    }
    cout << ans << endl;
  }


  return 0;
}