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

/**
 * @author icemore
 */
public class Main {
    
    int f(ArrayList<Integer> a)
    {
        int res=0;
        Stack<Integer> stack = new Stack<>();
        
        for (int i = 0; i < a.size(); i++) {
            while(!stack.empty() && stack.peek()<a.get(i))
                stack.pop();
            
            if(!stack.empty())
                res=Math.max(res, stack.peek()^a.get(i));
            stack.push(a.get(i));
        }
        
        return res;
    }
    
    void solve() throws IOException
    {
        int n=nextInt();
        ArrayList<Integer> a = new ArrayList<>(n);
        
        for (int i = 0; i < n; i++) {
            a.add(nextInt());
        }
        
        int res=f(a);
        Collections.reverse(a);
        res=Math.max(res, f(a));
        
        out.println(res);
    }
    
    //<editor-fold defaultstate="collapsed" desc="Template">
    
    double nextDouble() throws IOException
    {
        return Double.parseDouble(nextToken());
    }
    
    long nextLong() throws IOException
    {
        return Long.parseLong(nextToken());
    }
    
    int nextInt() throws IOException
    {
        return Integer.parseInt(nextToken());
    }
    
    String nextToken() throws IOException
    {
        while(st==null || !st.hasMoreTokens())
        {
            st = new StringTokenizer(br.readLine());
        }
        
        return st.nextToken();
    }
    
    void run() throws IOException
    {
        boolean onlineJudge = System.getProperty("ONLINE_JUDGE")!=null;
        Reader reader = onlineJudge ? new InputStreamReader(System.in) : new FileReader("input.txt");
        Writer writer = onlineJudge ? new OutputStreamWriter(System.out) : new FileWriter("output.txt");
        
        br = new BufferedReader(reader);
        out = new PrintWriter(writer);
        solve();
        out.close();   
    }
    
    public static void main(String[] args) throws IOException {
        new Main().run();
    }
    
    StringTokenizer st;
    BufferedReader br;
    PrintWriter out;
    //</editor-fold>
}
