#!/usr/bin/env python3
import sys

def main():
    N = int(input())
    A = list(map(int, input().split()))
    nums = [True] * 65
    # import math
    # # print(math.log2(max(A)))
    # # print(10 ** 18)
    # # print(2 ** 60)
    # # print(2 ** 60 > 10 ** 18)
    for aa in A:
        for i in range(65):
            if aa >> i & 1:
                nums[i] = False      
    for i, f in enumerate(nums):
        if f:
            print(2 ** i)
            return
if __name__ == '__main__':
    main()