# https://yukicoder.me/problems/no/3550



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

    a_list = []
    for a in A:
        array = []
        for k in range(30):
            array.append(a % 2)
            a //= 2
        a_list.append(array)
    
    answer = [0] * 30
    for k in reversed(range(30)):
        if k % 2 == 1:
            is_ok = False
            for i in range(len(a_list)):
                if a_list[i][k] == 1:
                    is_ok = True

            if is_ok:
                answer[k] = 1
            else:
                answer[k] = 0
        else:
            is_ok = True
            array = []
            for i in range(len(a_list)):
                if a_list[i][k] == 1:
                    array.append(i)

            if len(array) > 0:
                for l in range(k + 1, 30, 2):
                    if answer[l] == 1:
                        is_ok2 = False
                        for i in array:
                            if a_list[i][l] == 1:
                                is_ok2 = True
                        if not is_ok2:
                            is_ok = False
            else:
                is_ok = False
            
            if is_ok:
                answer[k] = 1
                a_list = [a_list[i] for i in array]
            else:
                answer[k] = 0

    ans = 0
    for k in range(30):
        ans += answer[k] * (2 ** k)
    print(ans)                                



        

        









if __name__ == "__main__":
    main()