#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
int main() {
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        long long a, b, c;
        cin >> a >> b >> c;
        if (c == 1) {
            cout << "-1" << endl;
            continue;
        }
        long long co = 0;
        if (a % c == 0) {
            a /= c;
            co++;
        }
        while (a > 0) {
            co++;
            if (a < c && a == 1) {
                co--;
            }
            a /= c;
            co++;
        }
        cout << b * (co-1) << endl;
    }
}