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.Stack;

public class Main
{
	public static void main(String args[])
	{
		InputReader in=new InputReader(System.in);
		int n=in.readInt();
		int arr[]=new int[n];
		int arr1[]=new int[n];
		for(int i=0;i<n;i++)
		{
			arr1[n-1-i]=arr[i]=in.readInt();
		}
		
		System.out.println(Math.max(f(arr),f(arr1)));
	}
	static long f(int arr[])
	{
		Stack<Integer> s=new Stack<Integer>();
		long maxim=0;
		for(int i:arr)
		{
			while((!s.isEmpty()) && (s.peek()<i))
				s.pop();
			if(!s.isEmpty())
				maxim=Math.max((s.peek()^i),maxim);
			s.push(i);	
		}
		return maxim;
	}
}

class InputReader {
    private InputStream stream;
    private byte[] buf = new byte[1024];
 
    private int curChar;
 
    private int numChars;
 
    public InputReader(InputStream stream) {
        this.stream = stream;
    }
 
    public int read() {
        if (numChars == -1)           throw new RuntimeException();
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                throw new RuntimeException();
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }
 
    public String readString() {
        final StringBuilder stringBuilder = new StringBuilder();
        int c = read();
        while (isSpaceChar(c))
            c = read();
        do {
            stringBuilder.appendCodePoint(c);
            c = read();        } while (!isSpaceChar(c));
        return stringBuilder.toString();
		    }
 
    public int readInt() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }
 
    public long readLong() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        long res = 0;
        do {
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }
 
    public boolean isSpaceChar(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }
}
