import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] pieces = new int[n];
        for (int i = 0; i < n; i++) {
            pieces[i] = sc.nextInt();
        }
        Arrays.sort(pieces);
        long k = sc.nextLong();
        double min = pieces[n - 1] / (double)k;
        double max = pieces[n - 1] + 1;
        for (int i = 0; i < 10000; i++) {
            double m = (min + max) / 2;
            long count = 0;
            for (int j = n - 1; j >= 0 && count < k && pieces[j] >= m; j--) {
                count += (long)(pieces[j] / m);
            }
            if (count >= k) {
                min = m;
            } else {
                max = m;
            }
        }
        System.out.println(java.math.BigDecimal.valueOf(min).toPlainString());
    }
}