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.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
public class MAX_XOR{//PRACTICE15
	public static void main(String args[]){
		FastScanner sc=new FastScanner(System.in);
        int n=sc.nextInt();
        int a[]=new int[n];
        for(int i=0;i<n;i++){
            a[i]=sc.nextInt();
        }
        Stack<Integer> s = new Stack<>();
        int max=0,ans=0;
        for(int i=0;i<n;i++){
            if(s.isEmpty())
                s.push(a[i]);
            else if(a[i]<s.peek()){
                max=a[i]^s.peek();
                if(max>ans)
                    ans=max;
                s.push(a[i]);
            }
            else{
                while(!s.isEmpty()){
                    if(a[i]>s.peek()){
                        max=a[i]^s.pop();
                        if(max>ans)
                            ans=max;
                    }
                    else{
                        max=a[i]^s.peek();
                        s.push(a[i]);
                        if(max>ans)
                            ans=max;
                        break;
                    }
                }
                if(s.isEmpty())
                    s.push(a[i]);
            }
        }
        System.out.println(ans);
	}
	static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(InputStream stream) {
            try {
                br = new BufferedReader(new
                    InputStreamReader(stream));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String nextLine() { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        }

        int nextInt() {
            return Integer.parseInt(next());
        }
    }
}