from sys import stdin


def main(inp, inps):
    N = int(inp())
    A = list(map(int, inp().split()))
    sum_A = 0
    for a in A:
        sum_A |= a
    ans = sum_A + 1
    for i, b in enumerate(map(int, (bin(sum_A)[2:])[::-1])):
        if not b:
            ans = 2**i
            break
    print(ans)


main(stdin.readline, stdin.readlines)