from sys import stdin, stdout
input = lambda: stdin.readline().rstrip()
write = stdout.write

def main():
    global A, Ret
    n = int(input())
    A = tuple(map(int, input().split()))

    Ret = []
    fp(n)
    ans = 0
    for x in Ret:
        pwr = 0
        for i, j in x:
            pwr += A[i] ^ A[j]
        ans = max(ans, pwr)
    print(ans)

def fp(n, d=0, dd=0, idx=0):
    nh = n // 2
    if not d:
        d = [0] * nh
    if not dd:
        dd = [0] * n
    if idx == n:
        pair = [[] for _ in [0] * nh]
        for i in range(n):
            pair[dd[i]].append(i)
        Ret.append(pair)
        return

    for i in range(nh):
        if d[i] == 0:
            d[i] = 1
            dd[idx] = i
            fp(n, d, dd, idx + 1)
            d[i] = 0
            break

    for i in range(nh):
        if d[i] == 1:
            d[i] = 2
            dd[idx] = i
            fp(n, d, dd, idx + 1)
            d[i] = 1

main()