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.Scanner;
import java.util.Stack;

public class Main {
	
	public static int solve(int[] num, int n){
		Stack<Integer> stack = new Stack<>();
		int ans = Integer.MIN_VALUE;
		for(int i = 0; i < n; ++i){
			if(!stack.isEmpty() && num[i] > num[stack.peek()]){
				stack.pop();
				--i;
			}else{
				if(!stack.isEmpty()){
					ans = Math.max(ans, num[i]^num[stack.peek()]);
				}
				stack.push(i);
			}
		}
		stack.clear();
		for(int i = n-1; i>=0; --i){
			if(!stack.isEmpty() && num[i] > num[stack.peek()]){
				stack.pop();
				++i;
			}else{
				if(!stack.isEmpty()){
					ans = Math.max(ans, num[i]^num[stack.peek()]);
				}
				stack.push(i);
			}
		}
		return ans;
	}

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = Integer.valueOf(sc.nextLine());
		String str = sc.nextLine();
		String[] str_arr = str.split(" ");
		int[] num = new int[n];
		for(int i = 0; i < n; ++i){
			num[i] = Integer.valueOf(str_arr[i]);
		}
		int ans = solve(num, n);
		System.out.println(ans);
	}

}

	        	   	 			 		 			  	  	