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

int main() {
    int Q;
    cin >> Q;
    assert(1<=Q&&Q<=20);
    while(Q--){
        long long A,B,C; cin >> A >> B >> C;
        assert(1<=A&&A<=1000000000LL);
        assert(1<=B&&B<=1000000000LL);
        assert(1<=C&&C<=1000000000LL);

        if(C==1){
            cout << -1 << endl;
            continue;
        }

        if(A<C){
            cout << B << endl;
            continue;
        }

        vector<long long> v;
        while(A>0){
            v.push_back(A%C);
            A /= C;
        }

        reverse(v.begin(),v.end());
        long long ans = 0;
        long long cnt = v[0]*C+v[1];

        if(2*C-2>=cnt) ans += 2;
        else ans += 3;

        ans += (long long)v.size() - 2;
        for(int i = 2; i < v.size(); ++i) if(v[i]) ans += 1;

        ans *= B;
        assert(1<=ans&&ans<=1000000000000000000LL);
        cout << ans << endl;
    }
    return 0;
}