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 codeforces;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;

public class D281 {
	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(in.readLine());
		int[] arr = new int[n];
		String[] s = in.readLine().split(" ");
		for (int i = 0; i < n; i++) {
			arr[i] = Integer.parseInt(s[i]);
		}

		int result = maxXor(arr);
		for (int i = 0, j = n - 1; i < j; i++, j--) {
			int temp = arr[i];
			arr[i] = arr[j];
			arr[j] = temp;
		}
		System.out.println(Math.max(result, maxXor(arr)));
	}

	private static int maxXor(int[] arr) {
		int n = arr.length;
		Stack<Integer> list = new Stack<>();
		int result = arr[0] ^ arr[1];
		for (int value : arr) {
			while (!list.isEmpty() && list.peek() < value) list.pop();
			if (!list.empty()) {
				result = Math.max(result, list.peek() ^ value);
			}
			list.push(value);
		}
		return result;
	}
}
