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

def check(x):
    cnt=0
    for l in L:
        cnt+=l//x
    return cnt>=k

ok,ng=0,10**18
while abs(ng-ok)>pow(10,-9):
    mid=(ok+ng)/2
    if check(mid):ok=mid
    else:ng=mid

print(ok)