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.ArrayList;
import java.util.List;
import java.util.Scanner;


public class Lambdabamserne1A {
	public static void main(String[] a) {
		new Lambdabamserne1A().run();
	}
	int MAXN = 100000+5;
	int[] ar = new int[MAXN];
	int topbit = 31;
	int N;
	public void run() {
		Scanner in = new Scanner(System.in);
		N = in.nextInt();
		for (int i = 0; i < N; i++)
			ar[i] = in.nextInt();
		
		while (true) {
			boolean any = false;
			boolean all = true;
			for (int i = 0; i < N; i++) {
				any |= top(i);
				all &= top(i);
			}
			if (any && !all)
				break;
			topbit--;
		}
		
		//System.err.println(topbit);
		
		//for (int i = 0; i < N; i++)
		//	System.out.println(top(i));
		
		int res = 0;
		int last = -1;
		for (int i = 0; i < N; i++) {
			if (top(i) && (i == 0 || !top(i-1))) {
				res = Math.max(res, test(i-1, last, ar[i]));
				if (last != -1)
					res = Math.max(res, test(last+1, i, ar[last]));
			}
			if (top(i) && (i == N-1 || !top(i+1))) {
				last = i;
			}
		}
		res = Math.max(res, test(last+1, N, ar[last]));
		
		System.out.println(res);
		//System.out.println(simple());
	}
	
	private int test(int a, int b, int n) {
		int maxseen = 0;
		int res = 0;
		for (int i = a; i != b; i += Integer.signum(b-a)) {
			if (ar[i] > maxseen) {
				maxseen = ar[i];
				res = Math.max(res, ar[i]^n);
			}
		}
		return res;
	}
	
	private int simple() {
		int res = 0;
		for (int a = 0; a < N; a++) {
			for (int b = a+2; b <= N; b++) {
				int max0 = -1;
				int max1 = -1;
				for (int i = a; i < b; i++) {
					if (ar[i] > max0) {
						max1 = max0;
						max0 = ar[i];
					}
					else if (ar[i] > max1) {
						max1 = ar[i];
					}
				}
				res = Math.max(res, max0^max1);
				if ((max0^max1) == 128869996) {
					System.err.println(a+" "+b);
				}
			}
		}
		return res;
	}

	private boolean top(int i) {
		return (ar[i] & 1<<topbit) != 0;
	}
}
