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

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
const ull mod = 1e9 + 7;
#define REP(i,n) for(int i=0;i<(int)n;++i)

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){
  os << "(" << v.first << ", " << v.second << ")"; return os;
}
template<class T> ostream& operator << (ostream& os, const vector<T> v){
  for(int i = 0; i < (int)v.size(); i++){if(i > 0){os << " ";} os << v[i];} return os;
}
template<class T> ostream& operator << (ostream& os, const vector<vector<T>> v){
  for(int i = 0; i < (int)v.size(); i++){if(i > 0){os << endl;} os << v[i];} return os;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll Q;
    cin >> Q;
    while(Q--){
    	ll A, B, C;
    	cin >> A >> B >> C;

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

    	ll cnt = 0;
    	ll res = (1ll<<60);
    	while(A>0){
    		res = min(res, cnt+(A+(C-2))/(C-1));
    		if(A%C){
    			A -= (A%C);
    		}else{
    			A /= C;
    		}
    		cnt++;
    	}
    	res = min(res, cnt);
    	cout << res*B << endl;
    }
    return 0;
}