N = int(input())

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

x = 0
y = 10 ** 9

K = int(input())

while x * (1 + 10 ** (-10)) < y:
    z = (x + y) / 2
    k = 0
    for l in L:
        
        k += l // z
        
    if k >= K:
        x = z
        
    else:
        y = z
        
print(x)