#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# FileName: 	code
# CreatedDate:  2020-08-17 16:53:46 +0900
# LastModified: 2020-08-18 00:40:36 +0900
#


def main():
    N = int(input())
    L = list(map(int, input().split()))
    K = int(input())
    left = 0
    right = 10**9
    t = 0
    while left+10**(-9) < right and t <= 10**2:
        middle = (left+right)/2
        sum_sticks = sum(l//middle for l in L)
        if sum_sticks < K:
            right = middle
        else:
            left = middle
        t += 1
    print(left)


if __name__ == "__main__":
    main()