import sys
input=lambda:sys.stdin.readline().rstrip()
N=int(input())
L=list(map(int,input().split()))
K=int(input())
m=[0.0,float(max(L))]
while m[1]-m[0]>10**(-10):
	mid=sum(m)/2
	count=0
	for i in L:
		count+=int(i/mid)
	m[K>count]=mid
print(m[1])