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.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.*;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Main {
    static IO io = new IO();
    static int MOD = (int) 1e9 + 7;

    public static void main(String[] args) throws Exception{
        int n = io.getInt(), max = 0;
        List<Integer> ls = io.getIntegerArray(n);
        Stack<Integer> st = new Stack<>();
        for(int a: ls){
            while (!st.isEmpty() && st.peek() < a){
                max = Math.max(max, st.pop() ^ a);
            }
            if(st.size() > 0)
                max = Math.max(max, st.peek() ^ a);
            st.push(a);
        }
        System.out.println(max);
    }
}

class IO {
    private BufferedReader br = null;
    private StringTokenizer st = null;

    public IO() {
        this(System.in);
    }

    public IO(InputStream is) {
        this.br = new BufferedReader(new InputStreamReader(is));
    }

    public List<String> getStringArray(int n) throws IOException {
        if (n == 0)
            return new ArrayList<>();
        List<String> res = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            res.add(getString());
        }
        return res;
    }

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

    public <T> T getCustom(Function<String, T> f)throws IOException{
        return f.apply(getString());
    }

    public <T> List<T> getCustomList(int n, Function<String, T> f) throws IOException{
        List<String> stringList = getStringArray(n);
        return stringList.stream().map(f).collect(Collectors.toList());
    }

    public List<Integer> getIntegerArray(int n) throws IOException {
        if (n == 0)
            return new ArrayList<>();
        List<String> res = getStringArray(n);
        return res.stream().map(Integer::parseInt).collect(Collectors.toList());
    }

    public Integer getInt() throws IOException {
        List<Integer> res = this.getIntegerArray(1);
        return res.size() == 0 ? 0 : res.get(0);
    }
}