#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

long long solve() {
  long long a, b, c;
  cin >> a >> b >> c;

  if (c == 1)
    return -1;

  vector<long long> ret;
  long long cur = 0;
  while (a > 1) {
    ret.push_back(cur + (a + c - 2) / (c - 1));
    if (a % c == 0) {
      a /= c;
    } else {
      a -= a % c;
    }
    ++cur;
  }
  ret.push_back(++cur);
  long long r = *min_element(ret.begin(), ret.end());
  return b * r;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int Q;
  cin >> Q;
  while (Q--) {
    cout << solve() << endl;
  }
  
  return 0;
}