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.util.*;
import java.io.*;
public class Main {
    public static void main(String args[]){
        InputReader in = new InputReader();
        PrintWriter out = new PrintWriter(System.out);
        Task solver = new Task();
        solver.solve(1, in, out);
        out.close();
    }
    static int mod = (int)1e9+7;

    static class Task{

        public void solve(int testNumber, InputReader in, PrintWriter out) {
//            int T = in.nextInt();
//            while (T-->0){
//
//            }
            int N = in.nextInt();
            int a[] = new int[N];
            for (int i = 0; i < N; i++)
                a[i] = in.nextInt();
            Stack<Integer> stack = new Stack<>();
            int res = 0;
            for (int i = 0; i < N; i++){
                while (!stack.isEmpty()){
                    int top = stack.peek();
                    int xor = top ^ a[i];
                    res = Math.max(res, xor);
                    if (a[i] > top){
                        stack.pop();
                    }else
                        break;
                }
                stack.push(a[i]);
            }
            out.println(res);
        }
    }
    static class InputReader {
        BufferedReader br;
        StringTokenizer st;
        public InputReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }
        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
        int nextInt() {
            return Integer.parseInt(next());
        }
        long nextLong() {
            return Long.parseLong(next());
        }
        double nextDouble() {
            return Double.parseDouble(next());
        }
        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}