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.*;
	import java.math.*;
	
	 
	 public class Main	{
	   static class Pair implements Comparable<Pair>{
//	   int a;
//	   int b;
//	   public Pair(){}
//	   public Pair(int x,int y){a=x;b=y;}
	   public int compareTo(Pair p){
		 return Double.compare(a, p.a);
	   }
//		   long a,b;
//		   public Pair(long x,long y){a=x;b=y;}
//		   public int compareTo(Pair p){
//				 return Long.compare(a, p.a);
//		   }
//		  
	   double a, b;
	   public Pair(double x, double y) {a=x;b=y;}
//		@Override
//		public int hashCode() {
//			final int prime = 31;
//			int result = 1;
//			result = prime * result + a;
//			result = prime * result + b;
//		   
//			return result;
//		}
		@Override
		public boolean equals(Object obj) {
			Pair cur = (Pair)obj;
			if((a==cur.a && b==cur.b))return true;
			return false;
		}
	 }
	static class TrieNode{
		int cnt;
		TrieNode[]child;
		public TrieNode() {
			cnt = 0;
			child = new TrieNode[10];
		}
	}
	  public static long gcd(long a,long b)
	  {
	    if(a<b)
	      return gcd(b,a);
	    if(b==0)
	      return a;
	    return gcd(b,a%b);
	    
	  }
	  static int lcm(int a,int b) {
		  return  a*b / (int)gcd(a,b);
	  }
	  
	  static long mod = 998244353;//(long)(1e9+7); //
	   
	    public static void main(String[] args) throws Exception {
	       new Thread(null, null, "Anshum Gupta", 99999999) {
	            public void run() {
	                try {
	                    solve();
	                } catch(Exception e) {
	                    e.printStackTrace();
	                    System.exit(1);
	                }
	            }
	        }.start();
	    }
	
	static long pow(long x,long y){
	    if(y == 0)return 1;
	    if(y==1)return x;
	    long a = pow(x,y/2);
	    a = (a*a)%mod;
	    if(y%2==0){
	        return a;
	    }
	    return (a*x)%mod;
	}
	
	static long mxx;
	static int mxN = (int)(2e6+5);
	static int mxV = (int)(2e5);
	static long[]fact,inv_fact;
	static long my_inv(long a) {
		return pow(a,mod-2);
	}
	static long bin(int a,int b) {
		if(a < b || a<0 || b<0)return 0;
	    return ((fact[a]*inv_fact[a-b])%mod * inv_fact[b])%mod;
	}
		static ArrayList<ArrayList<Integer>>adj;
		static boolean[]vis;
	static void make_facts() {
	  fact=new long[mxN];
	  inv_fact = new long[mxN];
	  fact[0]=inv_fact[0]=1L;
	  for(int i=1;i<mxN;i++) {
		   fact[i] = (i*fact[i-1])%mod;
		   inv_fact[i] = my_inv(fact[i]);
	  }
	}
	
	 public static void solve() throws Exception {
	   // solve the problem here
	   MyScanner s = new MyScanner();
	        out = new PrintWriter(new BufferedOutputStream(System.out), true);
	        int tc = 1;//s.nextInt();
	        mxx = (long)(1e18+5);
	//	        make_facts(); 
	//	        int mod = (int)1e9+7;
	        
	        while(tc-->0){
	        	int n = s.nextInt();
	        	long[]a = new long[n];
	        	for(int i=0;i<n;i++) {
	        		a[i] = s.nextLong();
	        	}
	        	Stack<Long> st = new Stack<Long>();
	        	long ans = 0;
	        	for(int i=0;i<n;i++) {
	        		while(!st.empty()) {
	        			long x = st.peek();
	        			ans = Math.max(ans, a[i] ^ x);
	        			if(x > a[i]) { // new maximum
	        				break;
	        			}
	        			st.pop();
	        		}
	        		st.add(a[i]);
	        	}
	        	out.println(ans);
	        }
	        	
	           
	        out.flush();
	}
	 
	     
	 
	 
	 
	    //-----------PrintWriter for faster output---------------------------------
	    public static PrintWriter out;
	 
	    //-----------MyScanner class for faster input----------
	    public static class MyScanner {
	        BufferedReader br;
	        StringTokenizer st;
	 
	        public MyScanner() {
	            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;
	        }
	    }
	    //--------------------------------------------------------
	}
