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.*;

//           THIS TEMPLATE MADE BY AKSH BANSAL.

public class Solution {
    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;
        }
    }
    static void sort(int a[]){ // int -> long
        ArrayList<Integer> arr=new ArrayList<>(); // Integer -> Long
        for(int i=0;i<a.length;i++)
        arr.add(a[i]);
        Collections.sort(arr);
        for(int i=0;i<a.length;i++)
        a[i]=arr.get(i);
        
    }
    private static long gcd(long a, long b){
        if(b==0)return a;
        return gcd(b,a%b);
    }
    private static long pow(long x,long y){
        if(y==0)return 1;
        long temp = pow(x, y/2);
        if(y%2==1){
            return x*temp*temp;
        }
        else{
            return temp*temp;
        }
    }

    static int mod = (int)1e9+7;
    static PrintWriter out;
    static FastReader sc ;
    public static void main(String[] args) throws IOException {
        sc = new FastReader();
        out = new PrintWriter(System.out);
        // primes();
        // ________________________________

        // _______________________________

        int n = sc.nextInt();
        int[]arr = new int[n];
        for(int i=0;i<n;i++){
            arr[i] = sc.nextInt();
        }
        // output.append().append("\n");
        solver(arr, n);
        // ________________________________
        out.flush();
    }

    public static void solver(int[]arr, int n) {
        int[] dp = new int[515];
        Arrays.fill(dp, Integer.MAX_VALUE);
        dp[0] = -1;
        for(int i=0;i<n;i++){
            for(int j=0;j<=512;j++){
                if(arr[i]>dp[j]){
                    dp[j^arr[i]] = Math.min(dp[j^arr[i]], arr[i]);
                }
            }
        }
        int res = 0;
        for(int i=0;i<=512;i++){
            if(dp[i]!=Integer.MAX_VALUE){
                res++;
            }
        }
        out.println(res);
        for(int i=0;i<=512;i++){
            if(dp[i]!=Integer.MAX_VALUE){
                out.print(i+" ");
            }
        }
    }
}