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.InputStreamReader;
import java.util.Stack;

public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int size = Integer.parseInt(br.readLine());

		int[] array = getIntArray(br.readLine().split(" "));

		Stack<Integer> stack = new Stack<>();
		int ans = Integer.MIN_VALUE;
		for (int num : array) {
			if (stack.isEmpty()) {
				stack.push(num);
			} else if (stack.peek() < num) {
				while (!stack.isEmpty() && stack.peek() < num) {
					int poppedEle = stack.pop();
					int currentAns = num ^ poppedEle;
					if (currentAns > ans) {
						ans = currentAns;
					}
				}
				if(!stack.isEmpty()) {
					int topEle = stack.peek();
					int currentAns = num ^ topEle;
					if (currentAns > ans) {
						ans = currentAns;
					}
				}
				stack.push(num);
			} else {
				int topEle = stack.peek();
				int currentAns = num ^ topEle;
				if (currentAns > ans) {
					ans = currentAns;
				}
				stack.push(num);
			}
		}
		System.out.println(ans);

	}

	// 134189790
	public static int[] getIntArray(String[] arr) {
		int[] array = new int[arr.length];
		int index = 0;
		for (String temp : arr) {
			array[index++] = Integer.parseInt(temp);
		}
		return array;
	}

}
