/* -*- coding: utf-8 -*-
 *
 * 1330.cc:  No.1330 Multiply or Divide - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 200000;
const int L = 31 * 31;

/* typedef */

typedef long long ll;

/* global variables */

int as[MAX_N], bs[MAX_N], cs[MAX_N], dp[L + 1];

/* subroutines */

/* main */

int main() {
  int n, m, p;
  scanf("%d%d%d", &n, &m, &p);

  int maxa = 0;
  for (int i = 0; i < n; i++) {
    scanf("%d", as + i);
    if (maxa < as[i]) maxa = as[i];
  }
  if (maxa > m) { puts("1"); return 0; }

  int k = 0;
  for (int i = 0; i < n; i++) {
    int b = as[i], dc = 1;
    while (b % p == 0) b /= p, dc++;
    if (b > 1) {
      bs[k] = b, cs[k] = dc;
      k++;
    }
  }
  if (k == 0) { puts("-1"); return 0; }

  int ma = m / maxa;
  memset(dp, -1, sizeof(dp));
  dp[0] = 1;
  for (int i = 0; i <= L; i++)
    if (dp[i] >= 0) {
      if ((ll)dp[i] > ma) {
	printf("%d\n", i + 1);
	return 0;
      }

      for (int j = 0; j < k; j++)
	if (i + cs[j] <= L)
	  dp[i + cs[j]] =
	    min<ll>(max<ll>(dp[i + cs[j]], (ll)dp[i] * bs[j]), ma + 1);
    }

  puts("-1");
  return 0;
}