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

def ok(x):
    cnt = 0
    for l in L:
        cnt += l // x
        if cnt >= k:
            return True
    return False

l = 0
r = 10 ** 9
for _ in range(100):
    mid = (l + r) / 2
    if ok(mid):
        l = mid
    else:
        r = mid
print((l + r) / 2)