import sys
input=lambda: sys.stdin.readline().rstrip()
n=int(input())
L=[int(i) for i in input().split()]
k=int(input())

def chk(x):
  ct=0
  for ln in L:
    ct+=int(ln/x)
  return ct>=k

l,r=0,max(L)
t=0
while r-l>10**(-9) and t<=10**2:
  mid=(l+r)/2
  if chk(mid):
    l=mid
  else:
    r=mid
  t+=1
print(l)