n=int(input())
al=list(map(int,input().split()))
k=int(input())
def zen(x):
	ans=0
	for i in al:
		if i>=x:ans+=i//x
	return ans>=k
	
ok,ng=0,10**10+1
cut=0
while(ng-ok>=10**-10 and cut<100):
	mid=(ok+ng)/2
	if zen(mid):ok=mid
	else:ng=mid
	cut+=1
print(ok)