n = int(input())
L = list(map(int,input().split()))
K = int(input())


def calc(x):
    count = 0
    for l in L:
        count += l//x
    return count

l = 0
r = 10**9+5

for i in range(80):
    m = (r+l)/2
    if calc(m) >= K:
        l = m
    else:
        r = m

print(l)