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 x

1, 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 s

l, 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

Copy

5
5 2 1 4 3

output

Copy

7

input

Copy

5
9 8 3 5 7

output

Copy

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}.

題意：給一個長度為 n 的序列，元素不重複，求任意區間中的最大元素與次大元素的異或值，然後再取這些值的最大值，注意區間長度任意。

思路：維護一個單調棧，找一個比a[i]大的元素（題目中說了最大的和第二大的）表示從i到那個元素這個區間內的最大值，注意要分別往後和往前找兩次（不然會有沒有遍歷到的情況，自己模擬一遍樣例2就明白了）