#include<bits/stdc++.h>
using namespace std;
#define REP(i,m,n) for(int i=(m);i<(n);i++)
#define rep(i,n) REP(i,0,n)
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define rall(c) (c).rbegin(),(c).rend()
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll inf=1e9+7;
const ll mod=998244353;
int main(){
    ll q;cin>>q;
    while(q){
        q--;
        ll a,b,c;cin>>a>>b>>c;
        if(c==1){
            cout<<-1<<endl;
            continue;
        }
        ll cnt=0;
        ll cnt2=inf;
        while(a!=0){
            cnt2=min(cnt2,cnt+(a%(c-1)==0?a/(c-1):a/(c-1)+1));
            if(a%c==0){
                a/=c;
            }else{
                a-=a%c;
            }
            cnt++;
        }
        cout<<min(cnt2,cnt)*b<<endl;
    }
}