import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

N = int(readline())
L = np.array(readline().split(),np.int64)
K = int(read())

def test(x):
    # 長さ x を K 本作れる
    return (L//x).astype(np.int64).sum() >= K

left = 0 # 可能
right = 10 ** 9 + 100 # 無理
for _ in range(100):
    x = (left + right) / 2
    if test(x):
        left = x
    else:
        right = x

print(left)