#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
#include <cctype>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <utility>
#include <fstream>

using namespace std;
typedef long long ll;
using ull = unsigned long long;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//template<typename T> T gcd(T a, T b) { a = abs(a), b = abs(b); while (b > 0) { tie(a, b) = make_pair(b, a % b); }return a; }
//mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long  mod = 998244353;

int main()
{

	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);

	ll n, m, P; cin >> n >> m >> P;
	vector<ll> a(n);
	ll tm = 1;
	map<ll, ll> b;
	for (auto& e : a) {
		cin >> e;
		chmax(tm, e);
		ll cnt = 1;
		while (e % P == 0) e /= P, cnt += 1;
		if (e > 1) {
			if (b.count(e)) chmin(b[e], cnt);
			else b[e] = cnt;
		}
	}
	if (tm > m) {
		cout << 1 << "\n";
		return 0;
	}
	ll mx = *max_element(a.begin(), a.end());

	if (mx == 1) {
		cout << -1 << "\n";
	}
	else {
		map<ll, ll> mp;
		mp[1] = 0;
		ll res = INF;

		auto update = [&](ll x, ll y) {
			if (mp.count(x)) chmin(mp[x], y);
			else mp[x] = y;
		};
		while (!mp.empty() and  mp.begin()->first <= m) {
			if (mp.begin()->first * tm > m) {
				chmin(res, mp.begin()->second + 1);
				mp.erase(mp.begin());
			}
			else {
				auto [t, cnt] = *mp.begin();
				if (cnt >= res) continue;
				mp.erase(mp.begin());
				for (auto [f, s] : b) {
					if (f == 1) continue;
					if(cnt + s < inf) update(t * f, cnt + s);
				}
			}
		}
		cout << res << "\n";
	}
}