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.*;
import java.util.*;

public class Main {
	static PrintWriter out = new PrintWriter(new BufferedWriter(
			new OutputStreamWriter(System.out)));

	public static void main(String[] args) throws IOException {
		Scan scan = new Scan();
		int n = scan.nextInt();
		int a[] = new int[n];
		int b[] = new int[n + 1];
		for (int i = 0; i < n; i++) {
			a[i] = scan.nextInt();
		}
		int count = 0;
		int ans = 0;
		for (int i = 0; i < n; i++) {
			if (count == 0) {
				count++;
				b[count] = a[i];
			}
			while (a[i] > b[count]&&count!=0) {
				ans = max(ans, a[i] ^ b[count]);
				// out.println(i + " " + count);
				count--;
			}
			if (count == 0) {
				count++;
				b[count] = a[i];
			}
			if (a[i] < b[count]) {
				ans = max(ans, a[i] ^ b[count]);
				count++;
				b[count] = a[i];
			}
			// for(int x = 0;x<n;x++){
			// out.print(b[x]+" ");
			// }
			// out.println(count);
		}
		// for(int i = 0;i<n;i++){
		// out.print(b[i]+" ");
		// }
		// out.println();
		out.println(ans);
		out.flush();

	}

	public static int max(int a, int b) {
		if (a > b)
			return a;
		return b;
	}
}

class Scan {

	BufferedReader buffer;
	StringTokenizer tok;

	Scan() {
		buffer = new BufferedReader(new InputStreamReader(System.in));
	}

	boolean hasNext() {
		while (tok == null || !tok.hasMoreElements()) {
			try {
				tok = new StringTokenizer(buffer.readLine());
			} catch (Exception e) {
				return false;
			}
		}
		return true;
	}

	String next() {
		if (hasNext())
			return tok.nextToken();
		return null;
	}

	String nextLine() {
		String s = null;
		try {
			s = buffer.readLine();
		} catch (Exception e) {
			return null;
		}
		return s;
	}

	char nextChar() {
		try {
			return ((char) buffer.read());
		} catch (Exception e) {
		}
		return '\0';
	}

	int nextInt() {
		return Integer.parseInt(next());
	}

	long nextLong() {
		return Long.parseLong(next());
	}

	double nextDouble() {
		return Double.parseDouble(next());
	}
}