from math import floor

n = int(input())
L = list(map(int, input().split()))
k = int(input())
eps = 1e-10

left = 0
right = max(L) + eps
while right - left > eps:
    mid = (left + right) / 2
    cnt = 0
    for i in range(n):
        cnt += floor(L[i] / mid)
    if cnt >= k:
        left = mid
    else:
        right = mid
print(left)