#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace atcoder;
using namespace std;
using ll = long long;
using mint = modint998244353;
int main() {
	int N;ll M, P;cin >> N >> M >> P;
	int K = 1000;
	vector<ll> A(K + 1, 0);
	bool ret = false;
	for (int i = 1;i <= N;i++) {
		ll a;cin >> a;
		if (a > M) {
			cout << 1 << endl;
			return 0;
		}
		int c = 0;
		while (a % P == 0) {
			c++;
			a /= P;
		}
		A[c] = max(A[c], a);
		if (a != 1) {
			ret = true;
		}
	}
	if (!ret) {
		cout << -1 << endl;
		return 0;
	}
	vector<ll> dp(K + 1, 1);
	ll ep = 1;
	for (int i = 0;i <= 35;i++) {
		if (A[i] == 0) {
			if (ep > M) continue;
			ep *= P;
			continue;
		}
		vector<ll> ndp(K + 1, 1);
		ll x = A[i];
		ll y = ep * A[i];
		for (int j = 1;j <= K;j++) {
			//iをつかわない
			ndp[j] = dp[j];
			if (dp[j] == M + 1) continue;
			//iをつかう
			//いっかいかけるでoverになるばあい
			if (y * ndp[j - 1] > M) {
				ndp[j] = M + 1;
				continue;
			}
			//ならなかったばあい
			if (i + 1 <= j) {
				ndp[j] = max(ndp[j], min(M + 1, x * ndp[j - i - 1]));
			}
		}
		swap(dp, ndp);
		ep *= P;
	}
	for (int i = 1;i <= K;i++) {
		if (dp[i] == M + 1) {
			cout << i << endl;
			return 0;
		}
	}
	
}