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}.
//package com.congli.codeforces;

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

public class C172Div2D implements Runnable {

	BufferedReader in;
	PrintWriter out;
	StringTokenizer tok = new StringTokenizer("");

	public static void main(String[] args) {
		new Thread(null, new C172Div2D(), "", 256 * (1L << 20)).start();
	}
	
	public void solve() throws IOException 
	{
		int n = readInt();
		Stack<Integer> stack = new Stack<Integer>();
		int result = 0;
		for(int i = 0; i < n; ++i)
		{
			int current_digit = readInt();
			if(stack.empty())
				stack.push(current_digit);
			else
			{
				while(!stack.empty() && current_digit > stack.peek())
				{
					result = Math.max(result, current_digit^stack.peek());
					stack.pop();
				}
				if(!stack.empty())
					result = Math.max(result, current_digit^stack.peek());
				stack.push(current_digit);
			}
		}
		out.println(result);
	}
	
	public void run() {
		try {
			long t1 = System.currentTimeMillis();
			if (System.getProperty("ONLINE_JUDGE") != null) {
				in = new BufferedReader(new InputStreamReader(System.in));
				out = new PrintWriter(System.out);
			} else {
				in = new BufferedReader(new FileReader("..\\Codeforces\\src\\com\\congli\\codeforces\\input.txt"));
				out = new PrintWriter(System.out);
			}
			Locale.setDefault(Locale.US);
			solve();
			in.close();
			out.close();
			long t2 = System.currentTimeMillis();
			System.err.println("Time = " + (t2 - t1));
		} catch (Throwable t) {
			t.printStackTrace(System.err);
			System.exit(-1);
		}
	}

	public String readString() throws IOException {
		while (!tok.hasMoreTokens()) {
			tok = new StringTokenizer(in.readLine());
		}
		return tok.nextToken();
	}

	public int readInt() throws IOException {
		return Integer.parseInt(readString());
	}

	public long readLong() throws IOException {
		return Long.parseLong(readString());
	}

	public double readDouble() throws IOException {
		return Double.parseDouble(readString());
	}
}



