#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;


ll solve(ll A, ll B, ll C){
  if(C == 1) return -1;
  if(A < C) return B;

  ll ret = 100000000000LL;
  ll x = 0;
  while(true){
    ret = min(ret, x + (A+C-2)/(C-1));
    if(A%C > 0){
      x++;
      A -= A%C;
    }
    if(A == 0) break;
    ret = min(ret, x + (A+C-2)/(C-1));
    x++;
    A /= C;
  }

  return B * ret;
}

int main(){
  int Q;
  cin >> Q;
  rep(i,Q){
    ll A, B, C;
    cin >> A >> B >> C;
    cout << solve(A, B, C) << endl;
  }
  
  return 0;
}