#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>

using namespace std;

typedef long long ll;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int Q;
    cin >> Q;
    for(int dum = 0; dum < Q; dum++){
        ll A, B, C;
        cin >> A >> B >> C;
        ll ans = 0;
        if(C == 1){
            cout << -1 << endl;
            return 0;
        }
        if(C == 2){
            ans = A*B;
            cout << ans << endl;
            return 0;
        }
        while(A != 0){
            if(A <= 2*C-2){
                if(A < C) ans += B;
                else ans += 2*B;
                break;
            }
            if(A%C != 0) ans += B;
            A -= (A%C);
            if(A != 0){
                A /= C;
                ans += B;
            }
        }
        cout << ans << endl;
    }
}