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.InputStreamReader;
import java.util.Random;
import java.util.Stack;
import java.util.StringTokenizer;

public class Xor {

    private static long max = 0;
    private static long max2 = 0;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        br.readLine();
        solve(br.readLine());
//        int t = 10;
//        while (t-- > 0) {
//            if (!generate()) break;
//        }
    }

    private static boolean generate() {
        Random random = new Random();
        int n = 0;
        while (n == 0) {
            n = random.nextInt(7);
        }
        StringBuilder builder = new StringBuilder();
        while (n-- > 0) {
            int num = 0;
            while (num == 0) {
                num = random.nextInt(10);
            }
            builder.append(num).append(" ");
        }
        String input = builder.toString();

        solve(input);
        test(input);

        System.out.println(input + "  solve : " + max + " test : " + max2);
        if (max2 != max) {
            System.out.println(input + "  failed");
            return false;
        }
        return true;
    }

    private static void test(String input) {
        max2 = 0;
        StringTokenizer tokens = new StringTokenizer(input);
        int arr[] = new int[tokens.countTokens()];
        int index = 0;
        while (tokens.hasMoreTokens()) {
            arr[index++] = Integer.parseInt(tokens.nextToken());
        }
        int m1, m2;
        for (int i = 0; i < arr.length; i++) {
            m1 = arr[i];
            m2 = -1;
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[j] > m1) {
                    m1 = arr[j];
                    m2 = arr[i];
                } else if (arr[j] > m2) {
                    m2 = arr[j];
                }
                long mm = m1 ^ m2;
                if (mm > max2) max2 = mm;
            }
        }
    }

    private static void solve(String input) {
        max = 0;
        Stack<Long> stack = new Stack<>();
        StringTokenizer tokens = new StringTokenizer(input);
        int pre = Integer.MAX_VALUE;
        while (tokens.hasMoreTokens()) {
            int num = Integer.parseInt(tokens.nextToken());
            if (num > pre) {
                de(stack, num);
            } else en(stack, num);

            pre = num;
        }
        if (!stack.isEmpty()) setResult(stack);
        System.out.println(max);
    }

    private static void setResult(Stack<Long> stack) {
        long pre = stack.pop();
        while (!stack.isEmpty()) {
            long num = stack.pop();
            checkMax(pre ^ num);
            pre = num;
        }
    }

    private static void checkMax(long num) {
        if (num > max) max = num;
    }

    private static void en(Stack<Long> stack, long num) {
        stack.push(num);
    }

    private static void de(Stack<Long> stack, long num) {
        while (!stack.isEmpty() && stack.peek() < num) {
            long pop = stack.pop();
            checkMax(num ^ pop);
            if (!stack.isEmpty()) checkMax(stack.peek() ^ pop);
        }
        en(stack, num);
    }
}


















