#define _USE_MATH_DEFINES

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <unordered_map> 
#include <unordered_set>
#include <functional>

using namespace std;

typedef pair<long long int, long long int> P;
typedef tuple<int, int, int> T;

long long int INF = 1e18;
long long int MOD = 1e9 + 7;

int main(){
	int Q;
	cin >> Q;
	for(int loop = 0; loop < Q; loop++){
		long long int A, B, C;
		cin >> A >> B >> C;
		if(C == 1){
			cout << -1 << endl;
			continue;
		}
		long long int ans = 0;
		while(A > 2 * (C - 1)){
			if(A % C == 0){
				A /= C;
			}else{
				A = A / C * C;
			}
			ans += B;
		}
		if(A > C - 1){
			ans += B * 2;
		}else{
			ans += B;
		}
		cout << ans << endl;
	}
	return 0;
}