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}.
/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
 

/* Name of the class has to be "Main" only if the class is public. */
public class Codechef {
    static int top;
     static List<Integer> stack;
           
    public static void stack_push(Integer element){
        stack.add(element);
        top++;
    }
    public static  int stack_pop(){
        if(top<0){
            System.out.println("Stack Underflow");
            return 0;
            
        }
        int temp=stack.get(top);
        stack.remove(top);
        top--;
        return temp;
    }
    public static int stack_peek(){
        if(top<0){
            System.out.println("Stack Underflow");
            return 0;
            
        }
        return stack.get(top);
    }
    public static boolean stack_isEmpty(){
        if(top==-1) return true;
        else return false;
    }
    
    public static void main (String[] args) throws java.lang.Exception    {
        // your code goes here
        
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb=new StringBuilder();
        int n=Integer.parseInt(br.readLine());
        String x[]=br.readLine().split(" ");
        int h[] =Arrays.stream(x).mapToInt(Integer::parseInt).toArray();
        
        stack=new LinkedList<Integer>();
        top=-1;
       int val=0;
        for(int i=0;i<n;i++){
            if(stack_isEmpty())
                stack_push(h[i]);
                
            val=Math.max(val,stack_peek()^h[i]);
            
            if(h[i]>stack_peek()){
                stack_pop();
                i--;
                continue;
            }
                 stack_push(h[i]);
        }
           System.out.println(val);
    }
}
