sub

import functools
import math
import itertools


def findsubsets(s, n):
    return list(itertools.combinations(s, n))


n = int(input())
a = []
for i in range(n):
    a.append(int(input()))

b = []
for i in range(1,n+1):
    temp = findsubsets(a,i)
    for e in temp:
        b.append(e)

all_beauty = []

for subs in b:
    if len(subs) > 0:
        s = sum(subs)
        r = functools.reduce(lambda x, y: x | y, subs)
        beauty = s/r
        all_beauty.append(beauty)

ans = max(all_beauty)
print(math.floor(ans*10000))