#include <bits/stdc++.h>
using namespace std;
#define int long long
#define REP(i,n) for(int i = 0;i < (int)(n);i++)
#define RREP(i,n) for(int i = (int)n-1;i >= 0;i--)
#define FOR(i,s,n) for(int i = s;i < (int)n;i++)
#define RFOR(i,s,n) for(int i = (int)n-1;i >= s;i--)
#define ALL(a) a.begin(),a.end()
template<class T>inline bool CHMAX(T&a,T b){if(a<b){a = b;return true;}return false;}
template<class T>inline bool CHMIN(T&a,T b){if(a>b){a = b;return true;}return false;}
constexpr long long INF = 1e18;

signed main(){
	int Q;
	cin>>Q;
	vector<int>ans;
	while(Q--){
		int A,B,C;
		cin>>A>>B>>C;
		if(C==1){
			ans.push_back(-1);
			continue;
		}
		int t = 0;
		vector<int>m;
		while(A){
			m.push_back(A%C);
			A/=C;
		}
		reverse(ALL(m));
		REP(i,m.size()){
			if(i+1==m.size()){
				if(i)t++;
				if(m[i])t++;
			}else if(m[i]&&m[i+1]&&m[i]*C+m[i+1]<=2*(C-1)){
				if(i)t+=2;
				i++;
				t+=2;
			}else{
				if(i)t++;
				if(m[i])t++;
			}
		}
		ans.push_back(t*B);
	}
	for(auto &e:ans)cout << e << endl;
}