using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace abs001_2
{
    class Program
    {
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            int[] L = Array.ConvertAll(Console.ReadLine().Split(' '),s => int.Parse(s));
            int K = int.Parse(Console.ReadLine());

            int min = 0;
            int max = int.MaxValue;
       
            for (var i = 0; i < 100; i++)
            {
                var middle = (max + min) / 2;

                if (check(middle, K)) min = middle;
                else max = middle;
            }

            Console.WriteLine(min);
        }

       static bool check(int x,int k)
        {
            int sum = 0;
            for(var i = 0; i < k; i++)
            {
                sum = x / k;
            }
            return sum == k;
        }

    }
}