#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

constexpr int INF = INT_MAX;
constexpr int MAX_N = int(1e5)+5;

int main() {
    int q;
    cin >> q;
    for(int i=0;i<q;i++){
        ll a, b, c, ans = 0;
        cin >> a >> b >> c;
        if(c == 1){
            cout << -1 << endl;
            continue;
        }
        while(a > 0){
            if(a<2*c-1){
                ans += b*((a-1)/(c-1)+1);
                a = 0;
            }
            else{
                if(a%c) ans += b;
                ans += b;
                a /= c;
            }
        }
        cout << ans << endl;
    }
    return 0;
}