B. Maximum Xor Secondary
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Bike loves looking for the second maximum element in the sequence. The second maximum element in the sequence of distinct numbers x 1, x 2, ..., x k (k > 1) is such maximum element x j, that the following inequality holds: .

The lucky number of the sequence of distinct positive integers x 1, x 2, ..., x k (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 s 1, s 2, ..., s n (n > 1). Let's denote sequence s l, s l + 1, ..., s r 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 s 1, s 2, ..., s n (1 ≤ s i ≤ 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}.