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.*;

public class Main
{
	public static void main(String[] args)
	{
		FastScanner in = new FastScanner(System.in);
		int n = in.nextInt();
		int[] s = new int[n + 5];
		int[] s2 = new int[n + 5];
		for (int i = 1; i <= n; i++)
		{
			s[i] = in.nextInt();
			s2[n - i + 1] = s[i];
		}
		
		int[] stack = new int[n + 5];
		int size = 0;
		int answer = 0;
		for (int i = 1; i <= n; i++)
		{
			while (size > 0 && stack[size - 1] < s[i])
				size --;

			stack[size++] = s[i];

			if (size >= 2)
				answer = Math.max(answer, stack[size - 1] ^ stack[size - 2]);
		}
		size = 0;
		for (int i = 1; i <= n; i++)
		{
			while (size > 0 && stack[size - 1] < s2[i])
				size --;

			stack[size++] = s2[i];

			if (size >= 2)
				answer = Math.max(answer, stack[size - 1] ^ stack[size - 2]);
		}
		System.out.println(answer);
	}
}
class FastScanner
{
	BufferedReader reader;
	StringTokenizer tokenizer;
	FastScanner(InputStream inputStream)
	{
		this.reader = new BufferedReader(new InputStreamReader(inputStream));
	}
	String nextToken()
	{
		while (tokenizer == null || ! tokenizer.hasMoreTokens())
		{
			try { tokenizer = new StringTokenizer(reader.readLine());
			} catch (Exception e){}
		}
		return tokenizer.nextToken();
	}
	int nextInt()
	{
		return Integer.parseInt(nextToken());
	}

}
