#include<bits/stdc++.h>
using namespace std;

long long solve_core(long long A, long long C){
    long long ans = 0;
    while (A > (C - 1) * 2){
        if (A % C) ++ans;
        A /= C;
        ++ans;
    }
    if (A < C){
        return ans + 1;
    }else {
        return ans + 2;
    }
}

long long solve(long long A, long long B, long long C){
    if (C == 1){
        return -1;
    }
    return B * solve_core(A, C);
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int Q;
    cin >> Q;
    while (Q--){
        long long A, B, C;
        cin >> A >> B >> C;
        cout << solve(A, B, C) << endl;
    }
    return 0;
}