#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#include <complex>
#define rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(),(x).end()
#define inf 1e18

using namespace std;

typedef long long llint;
typedef long long ll;
typedef pair<llint, llint> P;

ll n, m, p;
ll a[200005];
ll b[35];
ll dp[35][2005];

int main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> m >> p;
	m++;
	rep(i, 1, n) cin >> a[i];
	sort(a+1, a+n+1);
	
	if(m == 1){
		cout << 0 << endl;
		return 0;
	}
	if(a[n] >= m){
		cout << 1 << endl;
		return 0;
	}
	m = (m+a[n]-1)/a[n];
	
	ll ans = inf;
	rep(i, 1, n){
		ll cost = 0, mul = a[i];
		for(; mul % p == 0; mul /= p) cost++;
		chmax(b[cost+1], mul);
	}
	
	dp[0][0] = 1;
	rep(i, 0, 32){
		rep(j, 0, 2000){
			chmax(dp[i+1][j], dp[i][j]);
			if(j+i+1 <= 2000) chmax(dp[i][j+i+1], min(m, dp[i][j]*b[i+1]));
		}
	}
	rep(j, 0, 2000){
		if(dp[33][j] >= m){
			cout << j+1 << endl;
			return 0;
		}
	}
	cout << -1 << endl;
	
	return 0;
}