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.*;

/* Name of the class has to be "Main" only if the class is public. */
public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		Scanner sc = new Scanner(System.in);
		
// 		int t = sc.nextInt();
		
// 		while(t-- > 0) {
		    int n = sc.nextInt();
    		int[] arr = new int[n];
    		for(int i = 0; i < n; i++) {
    		    arr[i] = sc.nextInt();
    		}
    		long ans = getMax(arr);
    		System.out.println(ans);
// 		}
		
	}
	
	public static long getMax(int[] arr) {
	    Stack<Integer> st = new Stack<>();
	    int[] nge = new int[arr.length];
	    long maxXOR = 0;
	    for(int i = 0; i < arr.length; i++) {
	        while(!st.isEmpty() && arr[i] > arr[st.peek()]) {
	            nge[st.peek()] = arr[i]; 
	            st.pop();
	        }
	        st.push(i);
	    }
	    
	    for(int i = 0; i < arr.length; i++) {
	        if(nge[i] != 0) {
	            maxXOR = Math.max(maxXOR, arr[i]^nge[i]);
	            nge[i] = 0;
	        }
	    }
	    
	    
	    st = new Stack<>();
	    
	    for(int i = arr.length-1; i >= 0; i--) {
	        while(!st.isEmpty() && arr[i] > arr[st.peek()]) {
	            nge[st.peek()] = arr[i]; 
	            st.pop();
	        }
	        st.push(i);
	    }
	    
	    for(int i = 0; i < arr.length; i++) {
	        if(nge[i] != 0) {
	            maxXOR = Math.max(maxXOR, arr[i]^nge[i]);
	        }
	    }
	    
	    return maxXOR;
	}
}
