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.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;


public class ProblemB {

public static void main(String[] args) throws IOException {
		
		ProblemB solver = new ProblemB();
		solver.init();
		solver.solve();
	}
	
	private void init() {
		
		
	}
	
	private void solve() throws IOException {
		 
		Reader in = new Reader(System.in); 
		PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
		
		int N = in.nextInt();
		int[] stack = new int[N];
		int idx = 0;
		
		int best = 0;
		for (int i = 0; i < N; i++) {
			int k = in.nextInt();
			while (idx > 0 && stack[idx-1] < k) {
				idx--;
				best = Math.max(best, stack[idx] ^ k);
			}
			if (idx > 0) {
				best = Math.max(best, stack[idx - 1] ^ k);
			}
			stack[idx++] = k;
		}
		out.println(best);
		out.flush();
		out.close();
	}
	
	private static class Reader {
		
	    BufferedReader reader;
	    StringTokenizer tokenizer;
	
	    /** call this method to initialize reader for InputStream */
	    Reader(InputStream input) {
	        reader = new BufferedReader(
	                     new InputStreamReader(input) );
	        tokenizer = new StringTokenizer("");
	    }
	
	    /** get next word */
	    public String next() throws IOException {
	        while ( ! tokenizer.hasMoreTokens() ) {
	            //TODO add check for eof if necessary
	            tokenizer = new StringTokenizer(
	                   reader.readLine() );
	        }
	        return tokenizer.nextToken();
	    }
	
	    public int nextInt() throws IOException {
	        return Integer.parseInt( next() );
	    }
	    
	    public double nextDouble() throws IOException {
	        return Double.parseDouble( next() );
	    }
	    
	    public long nextLong() throws IOException {
	    	return Long.parseLong(next());
	    }
	}
}
