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.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;


public class A {
	
	static StringTokenizer st;
	static BufferedReader in;
	static int n;
	public static void main(String[] args) throws IOException {
		in = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		n = nextInt();
		int[]a = new int[n+1];
		for (int i = 1; i <= n; i++) {
			a[i] = nextInt();
		}
		int[]b = new int[n+1];
		for (int i = 1; i <= n; i++) {
			b[i] = a[n+1-i];
		}
		System.out.println(Math.max(calc(a), calc(b)));
		pw.close();
	}
	private static int calc(int[] a) {
		int max = -1;
		int[]prev = new int[n+1];
		for (int i = 2; i <= n; i++) {
			prev[i] = i-1;
		}
		for (int i = 2; i <= n; i++) {
			if (a[i] > a[i-1]) {
				int left = i-1;
				max = Math.max(max, (a[i] ^ a[left]));
				int max2 = a[left];
				while (left >= 1) {
					if (a[left] > a[i]) {
						prev[i] = left;
						break;
					}
					if (a[left] > max2) {
						max = Math.max(max, (a[left] ^ a[i]));
					}
					max2 = Math.max(max2, a[left]);
					left = prev[left];
				}
				if (left==0)
					prev[i] = 0;
			}
		}
		return max;
	}
	private static int nextInt() throws IOException{
		return Integer.parseInt(next());
	}
	
	private static long nextLong() throws IOException{
		return Long.parseLong(next());
	}
	
	private static double nextDouble() throws IOException{
		return Double.parseDouble(next());
	}
	
	private static String next() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }
}
