N=int(input())
A=list(map(int, input().split()))
P=[[] for _ in range(32)]
for a in A:
    l=a.bit_length()
    P[l].append(a)
B=[]
for l in range(32):
    if not P[l]: continue
    A=P[l]
    l-=1
    if not B:
        for a in A:
            if l==-1:
                B=A
            else:
                B.append(a^(1<<l))
    else:
        C=[]
        for b in B:
            C.append(b^(1<<l))
        if max(C)<max(A):
            for a in A:
                C.append(a^(1<<l))
            B=C
        else:
            for b in B:
                A.append(b)
            B=A
print(max(B))