def main():
    n = int(input())
    A = list(set(map(int, input().split())))
    B = []
    ans = 0
    S = [[] for _ in range(30)]
    for a in A:
        for i in range(30):
            if a >> i & 1:
                S[i].append(a)
    for i in range(29, -1, -1):
        if not i % 2 and S[i]:
            f = 1
            for j in range(i+1, 30, 2):
                if S[j] and not [1 for s in S[j] if s >> i & 1]:
                    f = 0
            if f:
                for j in range(30):
                    S[j] = [s for s in S[j] if s >> i & 1]
                ans ^= 1 << i
        else:
            if S[i]:
                ans ^= 1 << i
    return ans

print(main())