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.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayDeque;

public final class Solution {
    public static void main(String[] args) throws IOException {
        solution();
    }

    public static int LINE_LENGTH = 1000000;

    //No need of nextLine after integer as in Scanner
    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String nextLine() throws IOException {
            byte[] buf = new byte[LINE_LENGTH]; // line length
            int cnt = 0, c;
            while ((c = next()) != -1) {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = next();
            while (c <= ' ')
                c = next();
            boolean neg = (c == '-');
            if (neg)
                c = next();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = next()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = next();
            while (c <= ' ')
                c = next();
            boolean neg = (c == '-');
            if (neg)
                c = next();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = next()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = next();
            while (c <= ' ')
                c = next();
            boolean neg = (c == '-');
            if (neg)
                c = next();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = next()) >= '0' && c <= '9');

            if (c == '.') {
                while ((c = next()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte next() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }

    public static void solution() throws IOException {
        Reader in = new Reader();
        int n = in.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = in.nextInt();
        }
        int result = problem281DUtil(arr);
        int max = result;
        result = problem281DUtil(reverse(arr));
        max = max > result ? max : result;
        System.out.println(max);
        in.close();
    }
    private static int[] reverse(int arr[]) {
        for (int i = 0; i < arr.length / 2; i++) {
            int temp = arr[i];
            arr[i] = arr[arr.length - i - 1];
            arr[arr.length - i - 1] = temp;
        }
        return arr;
    }

    private static int problem281DUtil(int arr[]) {
        int result = arr[0] ^ arr[1];
        ArrayDeque<Integer> stack = new ArrayDeque<>();
        for (int i = 0; i < arr.length; i++) {
            while (!stack.isEmpty() && stack.peek() < arr[i]) {
                stack.pop();
            }
            int max = Integer.MIN_VALUE;
            if (!stack.isEmpty()) {
                max = stack.peek();
            }
            stack.push(arr[i]);
            if (stack.size() >= 2) {
                result = result > (max ^ arr[i]) ? result : max ^ arr[i];
            }
        }
        return result;
    }
}
