#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 dfs(int a, int c, int cnt) {
  if (a <= 0) return 0;
  if (a % c == 0) {
    if (cnt > 1) return 1 + dfs(a / c, c, 0);
    return 1 + min(dfs(a / c, c, 0), dfs(a - (c - 1), c, cnt + 1));
  } else {
    if (cnt > 1) return 1 + dfs(a / c * c, c, cnt + 1);
    return 1 + min(dfs(a / c * c, c, cnt + 1), dfs(max(0, a - (c - 1)), c, cnt + 1));
  }
}

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;
    }
    cout << B * dfs(A, C, 0) << endl;
  }
}