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}.
//package Round_172;

import java.util.*;
import java.io.*;

import static java.lang.Math.*;

public class d {

    void solve() throws Exception {
        int n = in.nextInt();
        int []a = new int[n];
        for (int i = 0; i<n; i++)
            a[i] = in.nextInt();
        int ans = count(a);
        int aa[] = new int[n];
        for (int i = 0; i<n; i++)
            aa[i] = a[n - i - 1];
        ans = max(ans, count(aa));
        out.println(ans);
    }
    
    int count(int []a){
        Stack<Integer> stack = new Stack<Integer>();
        int count=  0;
        for (int i = 0; i<a.length; i++){
            while (!stack.isEmpty() && stack.peek() < a[i])
                stack.pop();
            if (!stack.isEmpty())
                count = max(count, stack.peek() ^ a[i]);
            stack.push(a[i]);
        }
        return count;
    }

    FastScanner in;
    PrintWriter out;

    String input = "";
    String output = "";

    void run() {
        try {
            if (input.length() > 0) {
                in = new FastScanner(new BufferedReader(new FileReader(input)));
            } else
                in = new FastScanner(new BufferedReader(new InputStreamReader(
                        System.in)));
            if (output.length() > 0)
                out = new PrintWriter(new FileWriter(output));
            else
                out = new PrintWriter(System.out);

            solve();

            out.flush();
            out.close();
        } catch (Exception ex) {
            ex.printStackTrace();
            out.flush();
            out.close();
        } finally {
            out.close();
        }
    }

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

    class FastScanner {
        BufferedReader bf;
        StringTokenizer st;

        public FastScanner(BufferedReader bf) {
            this.bf = bf;
        }

        public String next() throws IOException {
            while (st == null || !st.hasMoreTokens())
                st = new StringTokenizer(bf.readLine());
            return st.nextToken();
        }

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

        public String nextLine() throws IOException {
            return bf.readLine();
        }

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

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

        public int[] readIntArray(int n) throws IOException {
            int[] array = new int[n];
            for (int i = 0; i < n; i++)
                array[i] = this.nextInt();
            return array;
        }

        public long[] readLongArray(int n) throws IOException {
            long[] array = new long[n];
            for (int i = 0; i < n; i++)
                array[i] = this.nextLong();
            return array;
        }

    }

}
