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.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;
import static java.lang.Math.*;

public class round172B {
    static BufferedReader br = new BufferedReader(new InputStreamReader(
            System.in));
    static StringTokenizer st = new StringTokenizer("");

    static int nextInt() throws Exception {
        return Integer.parseInt(next());
    }

    static String next() throws Exception {
        while (true) {
            if (st.hasMoreTokens()) {
                return st.nextToken();
            }
            String s = br.readLine();
            if (s == null) {
                return null;
            }
            st = new StringTokenizer(s);
        }
    }

    static int N;
    static int[] seq;
    
    public static void main(String[] args) throws Exception {
        N = nextInt();
        seq = new int[N];
        for (int i = 0; i < N; ++i)
            seq[i] = nextInt();
        int [] leftMax = new int [N];
        int [] last = new int [N];
        int [] rightMax = new int [N];
        Arrays.fill(leftMax, -1);
        Arrays.fill(rightMax, -1);
        int idx = -1;
        last[0] = -1;
        for(int i = 1 ; i < N ; ++i){
            if(seq[i] < seq[i - 1]){
                leftMax[i] = seq[i - 1];
                idx = i - 1;
                last[i] = idx;
                continue;
            }
            if(seq[i] > seq[i - 1]){
                int copIdx = idx;
                while(copIdx != -1 && seq[copIdx] < seq[i]){                    
                    copIdx = last[copIdx];
                }
                leftMax[i] = copIdx == -1 ? -1 : seq[copIdx];
                idx = copIdx;
                last[i] = idx;
            }
        }       
        idx = -1;
        Arrays.fill(last, 0);
        last[N - 1] = -1;
        for(int i = N - 2 ; i >= 0 ; --i){
            if(seq[i] < seq[i + 1]){
                rightMax[i] = seq[i + 1];
                idx = i + 1;
                last[i] = idx;
                continue;
            }
            if(seq[i] > seq[i + 1]){
                int copIdx = idx;
                while(copIdx != -1 && seq[copIdx] < seq[i]){                    
                    copIdx = last[copIdx];
                }
                rightMax[i] = copIdx == -1 ? -1 : seq[copIdx];
                idx = copIdx;
                last[i] = copIdx;
            }
        }       
        int ans = 0;
        for(int i = 0 ; i < N ; ++i){
            int left = leftMax[i];
            int right = rightMax[i];
            if(left != -1)
                ans = max(ans, seq[i] ^ left);
            if(right != -1)
                ans = max(ans, seq[i] ^ right);
        }
        System.out.println(ans);            
    }
}
