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

    num = 0
    for i in range(n):
        num |= A[i]

    bit = "{0:b}".format(num)

    ans_bit = 0
    for i in range(len(bit)):
        if bit[len(bit) - i - 1] == "0":
            ans_bit = i
            break

    if ans_bit == 0:
        print(num + 1)
    else:
        print(2 ** ans_bit)


if __name__ == "__main__":
    main()