#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second
template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = 0;
//---------------------------------//



ll solve(ll A, ll B, ll C) {
	if (C == 1) return -1;
	ll cnt = 0;
	bool f = false;
	
	while (A > 0) {
		if (A > C && A <= C*C && A <= 2*(C-1)) {
			f = true;
		}
		if (A % C > 0) {
			A -= A % C; cnt++;
		}
		if (A > 0) { A /= C; cnt++; }
	}
	if (f) cnt--;
	ll res = cnt * B;
	return res;
}

int main() {
	int Q;
	cin >> Q;
	while (Q--) {
		int A, B, C;
		scanf("%d %d %d", &A, &B, &C);
		cout << solve(A, B, C) << endl;
	}
	return 0;
}