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#include <iostream>
#include <vector>

using namespace std;

typedef long long ll;

const ll P = 90000007;

ll n, m;

ll Hasz(vector<ll>& H, vector<ll>& p, ll po, ll ko)
{
    return H[po] - p[ko - po + 1] * H[ko + 1];
}

bool Spr(vector<ll>& c, ll wzo)
{
    ll dl = c.size();
    if (dl < m) return false;
    vector<ll> p(dl);
    p[0] = 1;
    for (int i = 1; i < dl; ++i) p[i] = p[i - 1] * P;
    vector<ll> H(dl + 1);
    H[dl] = 0;
    for (int i = dl - 1; i >= 0; --i) H[i] = H[i + 1] * P + c[i];
    for (int i = 0; i <= dl - m; ++i) if (Hasz(H, p, i, i + m - 1) == wzo) return true;
    return false;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin >> n >> m;
    vector< vector<int> > K(n);
    int a, b;
    for (int i = 0; i < n; ++i)
    {
        cin >> a;
        for (int j = 0; j < a; ++j)
        {
            cin >> b;
            K[i].push_back(b);
        }
    }
    vector<ll> wzo(m);
    for (int i = 0; i < m; ++i) cin >> wzo[i];
    vector<ll> p(m);
    p[0] = 1;
    for (int i = 1; i < m; ++i) p[i] = p[i - 1] * P;
    vector<ll> H(m + 1);
    H[m] = 0;
    for (int i = m - 1; i >= 0; --i) H[i] = H[i + 1] * P + wzo[i];
    ll Hw = Hasz(H, p, 0, m - 1);
    vector<ll> c1, c2;
    c1.push_back(1);
    if (m == 1 && wzo[0] == 1)
    {
        cout << "1";
        return 0;
    }
    int nr = 2;
    while (1)
    {
        if (nr % 2 == 0)
        {
            c2.clear();
            for (int i = 0; i < c1.size(); ++i)
            {
                for (int j = 0; j < K[c1[i] - 1].size(); ++j) c2.push_back(K[c1[i] - 1][j]);
                if (Spr(c2, Hw))
                {
                    cout << nr;
                    return 0;
                }
                if (c2.size() > 10000 || nr == 1000)
                {
                    cout << "-1";
                    return 0;
                }
            }
        }
        else
        {
            c1.clear();
            for (int i = 0; i < c2.size(); ++i)
            {
                for (int j = 0; j < K[c2[i] - 1].size(); ++j) c1.push_back(K[c2[i] - 1][j]);
                if (Spr(c1, Hw))
                {
                    cout << nr;
                    return 0;
                }
                if (c1.size() > 10000 || nr == 1000)
                {
                    cout << "-1";
                    return 0;
                }
            }
        }
        ++nr;
    }
    return 0;
}