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.

输入描述:

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

输出描述:

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

备注:

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}.