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: <image>.

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}.
import java.util.*;
import java.io.*;

public final class Solution
{
    static int maxSecXor(int []arr,int n)
    {
        Stack<Integer> fwd=new Stack<>();
        int res=Integer.MIN_VALUE;
        fwd.push(0);
        for(int i=1;i<n;i++)
        {
            while(!fwd.isEmpty()&&arr[fwd.peek()]<arr[i])
            {
                res=(int)Math.max(res,arr[i]^arr[fwd.peek()]);
                fwd.pop();
            }
            fwd.push(i);
        }
        fwd.clear();
        fwd.push(n-1);
        for(int i=n-2;i>=0;i--)
        {
            while(!fwd.isEmpty()&&arr[fwd.peek()]<arr[i])
            {
                res=(int)Math.max(res,arr[i]^arr[fwd.peek()]);
                fwd.pop();
            }
            fwd.push(i);
        }
        return res;
    }
    
    public static void main(String []args) throws Exception
    {
        BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
       int n=Integer.parseInt(bf.readLine());
       int arr[]=new int[n];
       String s[]=bf.readLine().trim().split("\\s+");
       for(int i=0;i<n;i++)
         arr[i]=Integer.parseInt(s[i]);
       
       System.out.println(maxSecXor(arr,n));
    }
}