#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < (n); i++)
#define repr(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rep2(i, l, r) for (int i = (l); i < (r); i++)
#define rep2r(i, l, r) for (int i = (r) - 1; i >= (l); i--)
#define range(a) a.begin(), a.end()

using namespace std;
using ll = long long;

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
  int Q; cin >> Q;
  while (Q--) {
    ll A, B, C; cin >> A >> B >> C;
    if (C == 1) {
      cout << -1 << endl;
      continue;
    }
    ll ans = 0;
    while (A > 0) {
      if (A - (C - 1) <= 0) {
        ans += B;
        break;
      } else if (A - (C - 1) * 2 <= 0) {
        ans += 2 * B;
        break;
      }
      if (A % C == 0) {
        A /= C;
      } else {
        A = A / C * C;
      }
      ans += B;
    }
    cout << ans << endl;
  }
}