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

ok = 0
ng = 10**9


def is_ok(x):
    cnt = 0
    for i in range(N):
        num = L[i] // x
        cnt += num
        if cnt >= K:
            return 1
        
    return 0

while ng - ok > 10**(-10):
    mid = (ng + ok) / 2
    if is_ok(mid):
        ok = mid
    else:
        ng = mid
    # print(ok,ng)
print(ok)