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 class Input {
        private StringTokenizer tokenizer = null;
        private BufferedReader reader;
 
        public Input(InputStream inputStream) {
            reader = new BufferedReader(new InputStreamReader(inputStream));
        }
 
        public String nextLine() {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
 
        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                tokenizer = new StringTokenizer(nextLine());
            }
            return tokenizer.nextToken();
        }
 
        public int nextInt() {
            return Integer.parseInt(next());
        }
 
        public long nextLong() {
            return Long.parseLong(next());
        }
 
        public int[] nextIntArray(int n, int add) {
            int[] result = new int[n];
            for (int i = 0; i < n; i++) {
                result[i] = nextInt() + add;
            }
            return result;
        }
 
        public long[] nextLongArray(int n, long add) {
            long[] result = new long[n];
            for (int i = 0; i < n; i++) {
                result[i] = nextLong() + add;
            }
            return result;
        }
 
        public int[] nextIntArray(int n) {
            return nextIntArray(n, 0);
        }
 
    }
    
	public static void main (String[] args) throws java.lang.Exception
	{
		Input s=new Input(System.in);
		int t=1;
		while(t-->0)
		{
		    int n=s.nextInt();
		    int a[]=new int[n];
		    for(int i=0;i<n;i++)
		    {
		        a[i]=s.nextInt();
		    }
		    Stack<Integer> st=new Stack<>();
		    int max=0;
		    for(int i=0;i<n;i++)
		    {
		                while(!st.isEmpty() && a[i]>st.peek())
		                {
		                    st.pop();
		                }
		                st.push(a[i]);
		            
		            if(st.size()>=2)
		            {
		                int t1=st.pop();
		                int t2=st.pop();
		                //System.out.println(t1+" "+t2);
		                max=Math.max(max,t1^t2);
		                st.push(t2);
		                st.push(t1);
		            }
		        
		    }
		    st.clear();
		    //System.out.println(max);
		    for(int i=n-1;i>=0;i--)
		    {
		                while(!st.isEmpty() && a[i]>st.peek())
		                {
		                    st.pop();
		                }
		                st.push(a[i]);
		            
		            if(st.size()>=2)
		            {
		                int t1=st.pop();
		                int t2=st.pop();
		                //System.out.println(t1+" "+t2);
		                max=Math.max(max,t1^t2);
		                st.push(t2);
		                st.push(t1);
		            }
		        
		    }
		    
		    
		    System.out.println(max);
		    
		}
	}
}
