using System;
using System.Linq;

internal class Program
{
    public static void Main(string[] args)
    {
        var n = long.Parse(Console.ReadLine());
        var ls = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
        var k = long.Parse(Console.ReadLine());

        double minValue = 0;
        double maxValue = ls.Max();

        while (maxValue - minValue > 1e-13)
        {
            double mid = (minValue + maxValue)/2d;
            var sum = CalculateSum(n, ls, mid);
            if (sum >= k)
            {
                minValue = mid;
            }
            else
            {
                maxValue = mid;
            }
        }
        Console.WriteLine(minValue);
    }

    private static long CalculateSum(long n, long[] ls, double mid)
    {
        long sum = 0;
        for (int i = 0; i < n; i++)
        {
            sum += (long)(ls[i]/mid);
        }
        return sum;
    }
}