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.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Stack;
import java.util.StringTokenizer;

public class MaxXorSeconday {


	static int n;
	static int arr[];
	static int rev[];

	public static long solve(int a[])
	{
		int aux[] = new int[n];
		Stack<Integer> s = new Stack<Integer>();
		Arrays.fill(aux,-1);
		long res = 0;
		for(int i = 0 ; i < n ; ++i)
		{
			int curr = a[i];

			while(!s.isEmpty() && a[(Integer)(s.peek())] < curr)
			{
				aux[s.pop()] = curr;
			}
			s.push(i);

		}
		for(int i = 0 ; i < n ; ++i)
		{
			
			//System.out.println(a[i] +" "+aux[i]);
			if(aux[i] != -1)

				res = Math.max(res, (long)(a[i] ^ aux[i]));
		}
		return res;
	}
	public static void main(String[]args)throws Throwable
	{

		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();


		arr = new int[n];
		rev = new int[n];
		int lst = n - 1;
		for(int i = 0 ; i < n ; ++i)
		{
			arr[i] = sc.nextInt();
			rev[lst--] = arr[i];
		}	


		System.out.println(Math.max(solve(arr), solve(rev)));

	}



	static class Scanner
	{
		BufferedReader br;
		StringTokenizer st;


		Scanner(InputStream s)  { br = new BufferedReader(new InputStreamReader(s)); }

		String next() throws IOException
		{
			while(st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();

		}

		int nextInt() throws NumberFormatException, IOException { return Integer.parseInt(next()); }

	}
}
