import java.io.*;
import java.util.*;

class Reader {
    static BufferedReader reader;
    static StringTokenizer tokenizer;

    /**
     * call this method to initialize reader for InputStream
     */
    static void init(InputStream input) {
        reader = new BufferedReader(new InputStreamReader(input));
        tokenizer = new StringTokenizer("");
    }

    /**
     * get next word
     */
    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            //TODO add check for eof if necessary
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }
}

public class _1106 {

    public static void main(String args[]) throws IOException {
        int a;
        Reader.init(System.in);

        int n = Reader.nextInt();
        int graph[][] = new int[n][n];
        ArrayList<ArrayList<Integer>> st = new ArrayList<ArrayList<Integer>>();
        ArrayList<Integer> grp1 = new ArrayList<Integer>();
        ArrayList<Integer> grp2 = new ArrayList<Integer>();
        for (int i = 0; i < n; i++) {
            ArrayList<Integer> ar = new ArrayList<Integer>();
            do {
                a = Reader.nextInt();
                if (a != 0) {
                    graph[i][a - 1] = 1;
                    ar.add(a - 1);
                }

            }
            while (a != 0);
            st.add(ar);
        }


        if (n != 0) {
            grp1.add(0);
            for (int i = 1; i < n; i++) {
                if (graph[0][i] != 1) {
                    grp1.add(i);
                } else {
                    grp2.add(i);
                }
            }

            for (int i = 1; i < grp1.size(); i++) {
                int x = grp1.get(i);

                if (!st.get(x).isEmpty()) {
                    boolean frFlag = false;
                    Iterator it = st.get(x).iterator();
                    while (it.hasNext()) {
                        if (grp2.contains((Integer) it.next())) {
                            frFlag = true;
                            continue;
                        }
                    }

                    if (!frFlag) {
                        Integer rm = st.get(x).get(0);
                        //grp1.r
                        grp1.remove(rm);
                        grp2.add(rm);
                    }
                }

            }

            System.out.println(grp1.size());
            Iterator it1 = grp1.iterator();
            while (it1.hasNext()) {
                System.out.print(((Integer) it1.next() + 1) + " ");
            }
        } else {
            System.out.println(0);
        }

    }
}