# 偶数番目は全部1じゃなきゃいけなくて、奇数番目はどれかが1じゃなきゃいけない

from functools import reduce
from operator import or_

N = int(input())
A = list(map(int, input().split()))

res1 = 0
res2 = 0

for i in range(29, -1, -1):
    # print(f"{i:2}", " ".join(map(lambda a: f"{a:030b}", A)))
    if i & 1:
        res1 |= max(a & 1 << i for a in A)
    else:
        na = list(filter(lambda a: (a >> i & 1) == 1, A))
        if na and reduce(or_, na) & res1 == res1:
            res2 |= 1 << i
            A = na

res = res1 | res2
# print(res)
print(f"{res:030b}")