#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	int q; cin>>q;
    for(int i=0; i<q; i++){
        ll a, b, c;
        cin>>a>>b>>c;
        if(c==1){
            cout<<-1<<endl;
            continue;
        }
        ll x[50];
        int id=0;
        while(a){
            x[id]=a%c;
            a/=c;
            id++;
        }
        ll dp[50];
        dp[0]=0;
        for(int i=1; i<=id; i++){
            ll y=0;
            dp[i]=1e18;
            for(int j=1; j<=id; j++){
                y+=x[i-j];
                dp[i]=min(dp[i-j]+(y+c-2)/(c-1), dp[i]);
                y*=c;
            }
        }
        ll ans=1e18;
        ll y=0;
        for(int i=id-1; i>=0; i--){
            y+=x[i];
            ans=min(ans, dp[i]+(y+c-2)/(c-1)+i);
          y*=c;
        }
        ans*=b;
        cout<<ans<<endl;
    }
    return 0;
}