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 B {

    void solve() throws IOException {
        in("__std"); out("__std");

        int n = readInt();
        int best = 0;
        Stack<Integer> s = new Stack<Integer>();
        for (int i = 0; i < n; ++i) {
            int x = readInt();
            while (!s.isEmpty()) {
                int y = s.peek();
                int v = x ^ y;
                if (v > best) best = v;
                if (y > x) break;
                s.pop();
            }
            s.push(x);
        }
        println(best);

        exit();
    }

    void in(String name) throws IOException {
        if (name.equals("__std")) {
            in = new BufferedReader(new InputStreamReader(System.in));
        } else {
            in = new BufferedReader(new FileReader(name));
        }
    }

    void out(String name) throws IOException {
        if (name.equals("__std")) {
            out = new PrintWriter(System.out);
        } else {
            out = new PrintWriter(name);
        }
    }

    void exit() {
        out.close();
        System.exit(0);
    }

    char readChar() throws IOException {
        return (char) in.read();
    }

    int readInt() throws IOException {
        return Integer.parseInt(readToken());
    }

    long readLong() throws IOException {
        return Long.parseLong(readToken());
    }

    double readDouble() throws IOException {
        return Double.parseDouble(readToken());
    }

    String readLine() throws IOException {
        st = null;
        return in.readLine();
    }

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

    boolean eof() throws IOException {
        return !in.ready();
    }

    void print(String format, Object ... args) {
        out.print(new Formatter(Locale.US).format(format, args));
    }

    void println(String format, Object ... args) {
        out.println(new Formatter(Locale.US).format(format, args));
    }

    void print(Object value) {
        out.print(value);
    }

    void println(Object value) {
        out.println(value);
    }

    void println() {
        out.println();
    }

    StringTokenizer st;

    BufferedReader in;
    PrintWriter out;

    public static void main(String[] args) throws IOException {
        new B().solve();
    }
}
