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.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.OutputStream;
import java.util.Iterator;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.TreeSet;
import java.io.FileNotFoundException;
import java.util.HashSet;
import java.util.StringTokenizer;
import java.io.Writer;
import java.io.BufferedReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Asgar Javadov
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        F1KorneyKorneevichAndXOREasyVersion solver = new F1KorneyKorneevichAndXOREasyVersion();
        solver.solve(1, in, out);
        out.close();
    }

    static class F1KorneyKorneevichAndXOREasyVersion {
        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int n = in.nextInt();
            var a = in.readIntArray(n);

            HashSet<Integer>[] dp = new HashSet[512];
            for (int i = 0; i < dp.length; i++) {
                dp[i] = new HashSet<>();
            }

            var answer = new HashSet<Integer>();
            var seenSoFar = new TreeSet<Integer>();
            answer.add(0);
            for (int i = 0; i < n; ++i) {
                var ai = a[i];
                seenSoFar.add(ai);
                dp[ai].add(ai);
                answer.add(ai);
                for (var j : seenSoFar.subSet(0, ai)) {
                    for (var e : dp[j]) {
                        var x = e ^ ai;
                        dp[ai].add(x);
                        answer.add(x);
                        if (answer.size() == dp.length) break;
                    }
                }
            }

            out.println(answer.size());
            out.println(answer);
        }

    }

    static class OutputWriter extends PrintWriter {
        public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        }

        public OutputWriter(Writer writer) {
            super(writer);
        }

        public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        }

        public void println(Iterable<?> collection) {
            Iterator<?> iter = collection.iterator();

            if (iter.hasNext())
                print(iter.next());
            while (iter.hasNext()) {
                print(' ');
                print(iter.next());
            }
            println();
        }

        public void close() {
            super.close();
        }

    }

    static class InputReader extends BufferedReader {
        StringTokenizer tokenizer;

        public InputReader(InputStream inputStream) {
            super(new InputStreamReader(inputStream), 32768);
        }

        public InputReader(String filename) {
            super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    String line = readLine();
                    if (line == null) continue;
                    tokenizer = new StringTokenizer(line);
                } catch (IOException e) {
                    throw new RuntimeException();
                }
            }
            return tokenizer.nextToken();
        }

        public Integer nextInt() {
            return Integer.valueOf(next());
        }

        public int[] readIntArray(int size) {
            int[] array = new int[size];
            for (int i = 0; i < size; i++)
                array[i] = nextInt();
//        IntStream.generate(this::nextInt).limit(size).toArray();
            return array;
        }

    }
}

