#include <bits/stdc++.h>
using namespace std;
using lint = long long;
template<class T = int> using V = vector<T>;
template<class T = int> using VV = V< V<T> >;

int main() {
  cin.tie(nullptr); ios::sync_with_stdio(false);
  int q; cin >> q;
  while (q--) {
    lint a, b, c; cin >> a >> b >> c;
    if (c == 1) {
      cout << -1 << '\n';
      continue;
    }
    lint x = (a + c - 2) / (c - 1);
    lint t = 0;
    while (a) {
      if (a % c) {
        a = a / c * c;
        ++t;
      } else {
        a /= c;
        ++t;
      }
    }
    cout << min(t, x) * b << '\n';
  }
}