#!/usr/bin/env python3
# from typing import *

import sys
import io
import math
import collections
import decimal
import itertools
import bisect
import heapq


def input():
    return sys.stdin.readline()[:-1]


# sys.setrecursionlimit(1000000)

# _INPUT = """# paste here...
# """
# sys.stdin = io.StringIO(_INPUT)

INF = 10**10

def solve(N, A):
    for k in range(100):
        if len([a for a in A if a & (1<<k) == 0]) == N:
            return (1<<k)

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