#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int Q; cin >> Q;
    rep(_,Q) {
        ll A,B,C; cin >> A >> B >> C;
        if(C == 1) {
            cout << -1 << endl;
        } else {
            ll ans = 1e18;
            ll cnt = 0;
            while(A > 0) {
                ans = min(ans, cnt + (A + C - 1 - 1) / (C - 1));
                if(A % C != 0) {
                    A = A / C * C;
                } else {
                    A /= C;
                }
                cnt++;
            }
            cout << ans * B << endl;
        }
    }
}