import sys
sys.setrecursionlimit(10000)
n=int(input())
a=list(map(int,input().split()))
ans=[]
def f(l,now):
    global ans
    if len(l)==2:
        now+=l[0]^l[1]
        ans.append(now)
        return
    for i in range(1,len(l)):
        f(l[1:i]+l[i+1:],now+l[0]^l[i])
f(a,0)
print(max(ans))