#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
const ll INF = 1e18;
const int MOD = 1000000007;

void solve(){
    ll a,b,c;
    cin >> a >> b >> c;
    if(c==1){
        cout << -1 << endl;
        return;
    }
    ll cnt = 0;
    while(a>0){
        if(a%c == 0){
            a /= c;
            cnt ++;
        }else{
            if(a < c) a -= c,cnt ++;
            else if(c+1<= a && a<=2*(c-1) && c != 2) a = 0,cnt += 2;
            else{
                a -= a%c;
                cnt ++;
            }
        }
    }
    cout << b*cnt << endl;
    return;
}

int main(){
    int q;
    cin >> q;
    while(q--){
        solve();
    }
    return 0;
}