#include <bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)x.size())
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
  }*/

signed main(){
  int q;
  cin >> q;

  while(q--){
    int a, b, c;
    cin >> a >> b >> c;

    if(c == 1){
      cout << -1 << endl;
      continue;
    }

    vi d;
    while(a){
      d.emplace_back(a%c);
      a /= c;
    }

    reverse(all(d));

    int ans = 0, flag = 0;
    rep(i, 0, sz(d)){
      if(d[i] == 1 and i+1 < sz(d) and (d[i+1] and d[i+1] < c-1)){
        ans++;
        d[i] = 0;
        d[i+1]++;
      }

      if(d[i]){
        ans++;
        flag = 1;
      }
      if(i != sz(d)-1 and flag) ans++;

    }
    
    cout << ans*b << endl;
  }

  return 0;
}