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 Code0108 {


    static long answer(int a[]){
        List<Integer> one = new ArrayList<>();
        int n = a.length;
        int len[] = new int[a.length];
        int maxlen = 0;
        for (int i = 0; i < n; i++) {
            int x = a[i];
            int c = 0;

            while (x > 0){
                x = x/2;
                c++;
            }

            len[i] = c;

            maxlen = Math.max(maxlen,len[i]);
        }

         if(maxlen == 0){
             return 0;
         }
        long pow = (long)Math.pow(2,maxlen-1);

        for (int i = 0; i <n ; i++) {
            if(len[i] == maxlen){
                one.add(i);

            }
        }
        if(one.size() == n){
            for (int i = 0; i <n ; i++) {
                a[i] -= pow;
              //  System.out.print(a[i]+" ");
            }

           // System.out.println();
            return answer(a);
        }

        long maxans = 0;
        for (int i = 0; i <one.size() ; i++) {
             int pos = one.get(i);
             int left = 0;
             int right = n-1;
             if(i>0){
                 left = one.get(i-1)+1;
             }
             if((i+1)<one.size()){
                 right = one.get(i+1) - 1;
             }
             int secmax = 0;
            for (int j = pos-1; j >= left ; j--) {
                secmax = Math.max(secmax,a[j]);
                maxans = Math.max(maxans,a[pos]^secmax);
               // System.out.println(a[pos] + " " + secmax+ " "+ maxans);

            }
            secmax = 0;


            for (int j = pos+1; j <= right ; j++) {
                secmax = Math.max(secmax,a[j]);
                maxans = Math.max(maxans,a[pos]^secmax);
            }


        }
        return maxans;
    }
    public static void main(String args[]){
         Reader s = new Reader();
         int n = s.nextInt();
         int a[] = new int[n];

        for (int i = 0; i <n ; i++) {
            a[i] = s.nextInt();
        }

        System.out.println(answer(a));


    }
    static class Reader {

        private InputStream mIs;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

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

        public Reader(InputStream is) {
            mIs = is;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();

            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = mIs.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public String nextLine() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndOfLine(c));
            return res.toString();
        }

        public String next() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public boolean isEndOfLine(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

    }

}
