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


def C(x):
    cnt = 0
    for a in L:
        cnt += int(a // x + eps)
    return cnt >= K


l = 0
r = 10**9
for _ in range(222):
    m = (r + l) * 0.5
    if C(m):
        l = m
    else:
        r = m

print("{:.10f}".format(r))