human
Bike loves looking for the second maximum element in the sequence. The second maximum element in the sequence of distinct numbers x1, x2, ..., xk (k > 1) is such maximum element xj, that the following inequality holds: .

The lucky number of the sequence of distinct positive integers x1, x2, ..., xk (k > 1) is the number that is equal to the bitwise excluding OR of the maximum element of the sequence and the second maximum element of the sequence.

You've got a sequence of distinct positive integers s1, s2, ..., sn (n > 1). Let's denote sequence sl, sl + 1, ..., sr as s[l..r] (1 ≤ l < r ≤ n). Your task is to find the maximum number among all lucky numbers of sequences s[l..r].

Note that as all numbers in sequence s are distinct, all the given definitions make sence.

Input

The first line contains integer n (1 < n ≤ 105). The second line contains n distinct integers s1, s2, ..., sn (1 ≤ si ≤ 109).

Output

Print a single integer — the maximum lucky number among all lucky numbers of sequences s[l..r].

Examples

Input

5
5 2 1 4 3

Output

7

Input

5
9 8 3 5 7

Output

15

Note

For the first sample you can choose s[4..5] = {4, 3} and its lucky number is (4 xor 3) = 7. You can also choose s[1..2].

For the second sample you must choose s[2..5] = {8, 3, 5, 7}.
The above is tricky. Write me a correct solution in PYTHON3.

Can you provide a Python program to find the maximum number among all lucky numbers of sequences s[l?
assistant
#Here is Python program to find the maximum number among all lucky numbers of sequences s[l.

import sys
#t = -1
# def input():
#     global t
#     t += 1
#     return data[t]
#data=sys.stdin.readlines()
n=int(input())
a=list(map(int,input().split()))
b=[a[0]]
m=0
for i in range(1,n):
    if len(b)>0:
        m = max(m, b[-1] ^ a[i])
    while len(b)>0 and a[i]>b[-1]:
        m = max(m, b[-1] ^ a[i])
        b.pop()
    if len(b)>0:
        m = max(m, b[-1] ^ a[i])
    b.append(a[i])
    #print(b)
print(m)