This is an easier version of the problem with smaller constraints.

Korney Korneevich dag up an array a of length n. Korney Korneevich has recently read about the operation [bitwise XOR](https://en.wikipedia.org/wiki/Bitwise_operation#XOR), so he wished to experiment with it. For this purpose, he decided to find all integers x ≥ 0 such that there exists an increasing subsequence of the array a, in which the bitwise XOR of numbers is equal to x.

It didn't take a long time for Korney Korneevich to find all such x, and he wants to check his result. That's why he asked you to solve this problem!

A sequence s is a subsequence of a sequence b if s can be obtained from b by deletion of several (possibly, zero or all) elements.

A sequence s_1, s_2, … , s_m is called increasing if s_1 < s_2 < … < s_m.

Input

The first line contains a single integer n (1 ≤ n ≤ 10^5).

The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ 500) — the elements of the array a.

Output

In the first line print a single integer k — the number of found x values.

In the second line print k integers in increasing order x_1, x_2, … x_k (0 ≤ x_1 < … < x_k) — found x values.

Examples

Input


4
4 2 2 4


Output


4
0 2 4 6 


Input


8
1 0 1 7 12 5 3 2


Output


12
0 1 2 3 4 5 6 7 10 11 12 13 

Note

In the first test case:

  * To get value x = 0 it is possible to choose and empty subsequence 
  * To get value x = 2 it is possible to choose a subsequence [2] 
  * To get value x = 4 it is possible to choose a subsequence [4] 
  * To get value x = 6 it is possible to choose a subsequence [2, 4] 
import java.util.*;
import java.io.*;
//import javafx.util.*;

public class Solution
{
       static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;
 
        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }
 
        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(
                new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }
 
        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n') {
                    if (cnt != 0) {
                        break;
                    }
                    else {
                        continue;
                    }
                }
                buf[cnt++] = (byte)c;
            }
            return new String(buf, 0, cnt);
        }
 
        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ') {
                c = read();
            }
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
 
            if (neg)
                return -ret;
            return ret;
        }
 
        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }
 
        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
 
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
 
            if (c == '.') {
                while ((c = read()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }
 
            if (neg)
                return -ret;
            return ret;
        }
 
        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0,
                                 BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }
 
        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }
 
        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }
    static int parent(int x , int p[])
    {
           if(p[x] == x)
           return x;
           
           return (p[x] = parent(p[x],p));
    }
    
    static void union(int a , int b , int p[] , int size[])
    {
           a = parent(a,p);
           b = parent(b,p);
           
           if(size[a] < size[b])
           {
                  int temp = a;
                  a = b;
                  b = temp;
           }
           p[b] = a;
           size[a] += size[b];
    }
   // int ass;
    
    static long mod = 1000000007;
    static long pow(long a , long b)
    {
           if(b == 0)
           return 1;
           
           long ans = pow(a,b/2);
           if(b%2 == 0)
           return ans*ans%mod;
           
           return ans*ans%mod*a%mod;
    }
    
    
    
    
  public static void main(String []args) throws IOException
  {
         Reader sc = new Reader();
         int n = sc.nextInt();
         int arr[] = new int[n];
         for(int i = 0 ; i < n ; i++)
         {
                arr[i] = sc.nextInt();
         }
         int min[] = new int[513];
         for(int i = 0 ; i <= 512 ; i++)
         {
                min[i] = Integer.MAX_VALUE;
         }
         for(int i = 0 ; i < n ; i++)
         {
                for(int j = 0 ; j <= 512 ; j++)
                {
                       if(min[j] < arr[i])
                       {
                              min[j^arr[i]] = Math.min(min[j^arr[i]] , arr[i]);
                       }
                }
                min[arr[i]] = Math.min(min[arr[i]] , arr[i]);
         }
         
         int ans = 0;
         StringBuffer str = new StringBuffer("");
         min[0] = 0;
         for(int i = 0 ; i <= 512 ; i++)
         {
                if(min[i] != Integer.MAX_VALUE)
                {
                ans++;
                str.append(i + " ");
                }
         }
         System.out.println(ans);
         System.out.println(str);
  }
}