#!/usr/bin/env python3
import sys

def main():
    N = int(input())
    A = list(map(int, input().split()))
    nums = [True] * 60
    for aa in A:
        for i in range(60):
            if aa >> i & 1:
                nums[i] = False            
    for i, f in enumerate(nums):
        if f:
            print(2 ** i)
            return  

if __name__ == '__main__':
    main()