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

from math import floor
def check(m):
    val = 0
    for i in range(N):
        val += floor(L[i]/m)
    return val >= K    

yes = 10**-9
no = 10 ** 18
for i in range(200):
    mid = (yes + no)/2
    if check(mid):
        yes = mid
    else:
        no = mid
print(yes)