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 Codeforces {
	FastScanner in;
	PrintWriter out;

	int[] a;
	int ans = 0;
	int[] stack;
	int sp;
	
	int check(int[] a) {
		sp = 0;
		int ans = 0;
		for (int i = 0; i < a.length; i++) {
			while (sp > 0 && stack[sp - 1] < a[i]) {
				sp--;
			}
			if (sp != 0) {
				ans = Math.max(ans, stack[sp - 1] ^ a[i]);
			}
			stack[sp++] = a[i];
		}
		return ans;
	}
	
	void solve() {
		int n = in.nextInt();
		a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = in.nextInt();
		}
		stack = new int[n];
		ans = check(a);
		int i = 0, j = n - 1;
		while (i < j) {
			int t = a[i];
			a[i] = a[j];
			a[j] = t;
			i++;
			j--;
		}
		ans = Math.max(ans, check(a));
		out.println(ans);
	}

	void run() {
		in = new FastScanner();
		out = new PrintWriter(System.out);
		solve();
		out.close();
	}

	class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		FastScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));

		}

		String next() {
			while (st == null || !st.hasMoreTokens()) {

				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

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

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

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

	public static void main(String[] args) {
		new Codeforces().run();
	}
}