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

public class Solution {
	
	public static final int max = Integer.MAX_VALUE;
	
    public static void main (String[] args) throws IOException{
    	FastReader f=new FastReader();
    	int n = f.nextInt();
    	int[] a = new int[n];
    	for (int i=0;i<n;i++) a[i] = f.nextInt();
    	
    	Stack<Integer> st = new Stack<>();
    	st.push(a[0]);
    	int ans = 0;
    	for (int i=1;i<n;i++) {
    		while (!st.isEmpty() && a[i]>st.peek()) {
    			ans = Math.max(ans, st.pop()^a[i]);
    		}
    		st.push(a[i]);
    	}
    	
    	st = new Stack<>();
    	st.push(a[n-1]);
    	for (int i=n-2;i>=0;i--) {
    		while (!st.isEmpty() && a[i]>st.peek()) {
    			ans = Math.max(ans, st.pop()^a[i]);
    		}
    		st.push(a[i]);
    	}
    	System.out.println(ans);
    }
    
	public static int binlog( int bits ){
        int log = 0;
        if( ( bits & 0xffff0000 ) != 0 ) { bits >>>= 16; log = 16; }
        if( bits >= 256 ) { bits >>>= 8; log += 8; }
        if( bits >= 16  ) { bits >>>= 4; log += 4; }
        if( bits >= 4   ) { bits >>>= 2; log += 2; }
        return log + ( bits >>> 1 );
    }

    static class FastReader 
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() 
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
  
}
