from math import sqrt,sin,cos,tan,ceil,radians,floor,gcd,exp,log,log10,log2,factorial,fsum
from heapq import heapify, heappop, heappush
from bisect import bisect_left, bisect_right
from copy import deepcopy
import copy
import random
from collections import deque,Counter,defaultdict
from itertools import permutations,combinations
from decimal import Decimal,ROUND_HALF_UP
#tmp = Decimal(mid).quantize(Decimal('0'), rounding=ROUND_HALF_UP)
from functools import lru_cache, reduce
#@lru_cache(maxsize=None)
from operator import add,sub,mul,xor,and_,or_,itemgetter
INF = 10**18
mod1 = 10**9+7
mod2 = 998244353

#DecimalならPython
#再帰ならPython!!!!!!!!!!!!!!!!!!!!!!!!!!


'''
両端以外を2回とる


'''

N = int(input())
A = list(map(int, input().split()))

tmp = A[0]^A[0]
for i in range(1,N):
    tmp ^= A[i]
    tmp ^= A[i]

ans = 0
for i in range(N):
    for j in range(i+1,N):
        ans = max(ans,tmp^A[i]^A[j])

print(ans)