#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
long long solve () {
  long long a, b, c;
  cin >> a >> b >> c;
  if (c == 1) return -1;
  for (int i = 1; ; i++) {
    if ((c - 1) * 2 >= a) a -= c - 1;
    else if (a % c == 0) a /= c;
    else a -= a % c;
    if (a <= 0) return b * i;
  }
}
signed main() {
  ios::sync_with_stdio(false); cin.tie(0);
  int q;
  cin >> q;
  while (q--) cout << solve() << '\n';
  return 0;
}