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 B {
	static FastReader sc=null;
			
	public static void main(String[] args) {
		sc=new FastReader();
		int n=sc.nextInt();
		int a[]=sc.readArray(n);
		
		Stack<Integer> s=new Stack<>();
		int right[]=new int[n],left[]=new int[n];
		Arrays.fill(right, -1);
		Arrays.fill(left, -1);
		
		for(int i=0;i<n;i++) {
			if(s.empty())s.push(i);
			else {
				while(!s.empty()) {
					int id=s.pop();
					if(a[id]<a[i]) right[id]=i;
					else {
						s.push(id);
						break;
					}
				}
				s.push(i);
			}
		}
		for(int i=n-1;i>=0;i--) {
			if(s.empty())s.push(i);
			else {
				while(!s.empty()) {
					int id=s.pop();
					if(a[id]<a[i]) left[id]=i;
					else {
						s.push(id);
						break;
					}
				}
				s.push(i);
			}
		}
		int max=0;
		for(int i=0;i<n;i++) {
			if(right[i]!=-1) max=Math.max(max, a[i]^a[right[i]]);
			if(left[i]!=-1)max=Math.max(max, a[i]^a[left[i]]);
		}
		System.out.println(max);
		
	}
	
	
	
	
	static int[] reverseSort(int a[]) {
		ArrayList<Integer> al=new ArrayList<>();
		for(int i:a)al.add(i);
		Collections.sort(al,Collections.reverseOrder());
		for(int i=0;i<a.length;i++)a[i]=al.get(i);
		return a;
	}
	static int[] reverse(int a[]) {
		ArrayList<Integer> al=new ArrayList<>();
		for(int i:a)al.add(i);
		Collections.reverse(al);
		for(int i=0;i<a.length;i++)a[i]=al.get(i);
		return a;
	}
	static char[] reverse(char a[]) {
		ArrayList<Character> al=new ArrayList<>();
		for(char i:a)al.add(i);
		Collections.reverse(al);
		for(int i=0;i<a.length;i++)a[i]=al.get(i);
		return a;
	}
	static int gcd(int a,int b) {
		if(b==0)return a;
		else return gcd(b,a%b);
	}
	static long gcd(long a,long b) {
		if(b==0)return a;
		else return gcd(b,a%b);
	}
	
	static int[] ruffleSort(int a[]) {
		ArrayList<Integer> al=new ArrayList<>();
		for(int i:a)al.add(i);
		Collections.sort(al);
		for(int i=0;i<a.length;i++)a[i]=al.get(i);
		return a;
	}
	
	static void print(int a[]) {
		for(int e:a) {
			System.out.print(e+" ");
		}
		System.out.println();
	}
	static void print(long a[]) {
		for(long e:a) {
			System.out.print(e+" ");
		}
		System.out.println();
	}
	
	static class FastReader 
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastReader() 
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
        int[] readArray(int n) {
    		int a[]=new int [n];
    		for(int i=0;i<n;i++) {
    			a[i]=sc.nextInt();
    		}
    		return a;
    	}
    } 
}






