from sys import stdin


def main():
    def func(a, p):
        n = len(a)
        if n == 2:
            pwr.append(p ^ (a[0] + a[1]))
            return
        for i in range(1, n):
            a_ = a[1:i] + a[i+1:]
            p_ = p ^ (a[0] + a[i])
            func(a_, p_)

    input = lambda: stdin.readline()[:-1]
    N = int(input())
    A = list(map(int, input().split()))

    pwr = []
    func(A, 0)
    print(max(pwr))


main()