from sortedcontainers import SortedList

def dfs():
    global ans, sum0
    if not S:
        ans = max(ans, sum0)
        return
    a = S.pop(0)
    for b in range(len(S)):
        c = S.pop(b)
        sum0 += A[a] ^ A[c]
        dfs()
        S.add(c)
        sum0 -= A[a] ^ A[c]
    S.add(a)

N = int(input())
A = list(map(int, input().split()))
S = SortedList(range(N))
ans = 0
sum0 = 0
dfs()
print(ans)