n = int(input())
l = list(map(int,input().split()))
k = int(input())

ok=0
ng=10**9+1

def judge(mid):
    cnt=0
    for ll in l:
        cnt += ll//mid
    if cnt >= k:
        return 1
    else:
        return 0

while ng - ok > 0.000000001:
    mid = (ng+ok)/2 #少数の場合：/
    if judge(mid):
        ok = mid
    else:
        ng = mid
    #print(ok,ng)
print(ok)