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

long long count(long long a, long long c) {
  if (a < c) {
    return 1;
  }
  if (a % c == 0) {
    return count(a / c, c) + 1;
  } else {
    return min (count(a / c, c) + 2, (a - 1) / (c - 1) + 1);
  }
}
int main() {
  int q;
  cin>>q;
  for (int i=0; i<q; i++) {
    long long a, b, c;
    cin>>a>>b>>c;
    if (c == 1) {
      cout<<-1<<endl;
      continue;
    }
    cout<<count(a, c) * b<<endl;
  }
}