1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.util.LinkedList;
import java.io.InputStream;

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

    static class EKS_PLAYAROUND {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int N = in.nextInt();
            int M = in.nextInt();
            ArrayList<Integer> H[] = new ArrayList[N + 1];
            int MAX_L = 0;
            for (int i = 1; i <= N; i++) {
                H[i] = new ArrayList<>();
                int L = in.nextInt();
                MAX_L = Math.max(L, MAX_L);
                for (int j = 0; j < L; j++) {
                    H[i].add(in.nextInt());
                }
            }
            int S[] = new int[M];
            for (int i = 0; i < M; i++) S[i] = in.nextInt();
            ArrayList<Integer> current = new ArrayList<>();
            current.add(1);
            if (S.length == 1 && S[0] == 1) {
                out.println(1);
                return;
            }

            for (int day = 2; day <= 80000; day++) {
                LinkedList<Integer> next = new LinkedList<>();
                for (Integer a : current) {
                    next.addAll(H[a]);
                }

                current = new ArrayList<>(next.size());
                for (Integer a : next) {
                    current.add(a);
                }
                if (contains(current, S)) {
                    out.println(day);
                    return;
                }

                if ((long) MAX_L * current.size() * S.length > 5000000) {
                    out.println("-1");
                    return;
                }
            }
        }

        private boolean contains(ArrayList<Integer> current, int[] s) {
            for (int i = 0; i < current.size() - s.length + 1; i++) {
                boolean wrong = false;
                for (int j = 0; j < s.length; j++) {
                    if (current.get(i + j) != s[j]) {
                        wrong = true;
                        break;
                    }
                }
                if (!wrong) return true;
            }
            return false;
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

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

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}