#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;

#define N 200010

const int mod = int(1e9 + 7);

int n, m;
vector<int>vi[N];
int vst[N], p[N], q[N];
int P[N];
void sol()
{
    // cout << "??:" << n << ' ' << m << '\n';
    for (int i = 1; i <= m; i ++) vst[i] = -1;
    for (int i = 1; i <= n; i ++)
    {
        int k; cin >> k;
        while (k --) 
        {
            int x;
            cin >> x;
            vi[i].push_back(x);
        }
    }
    for (int i = 1; i <= m; i ++) cin >> p[i];
    for (int i = 1; i <= m; i ++) q[p[i]] = i;
    P[0] = 1;
    for (int i = 1; i <= m; i ++) P[i] = (P[i - 1] + P[i - 1]) % mod;

    set<int>S;
    for (int i = 1; i <= n; i ++)S.insert(i);

    int sum = 0, ans = 0;

    for (int t = 0;; t ++)
    {
        if (S.empty()) break;
        vector<int>era;
        vector<int>v;
        for (int i : S)
        {
            if (vi[i].size() <= t)era.push_back(i);
            else 
            {
                int x = vi[i][t];
                if (vst[x] == -1) 
                {
                    vst[x] = t;
                    v.push_back(x);
                }
            } 
        }
        for (int x : era)S.erase(x);
        int num = 0;
        for (int x : v)ans = (ans + P[num]) % mod, num ++;
        sum = (sum + P[num]) % mod;
    }
    for (int i = 1; i <= m; i ++) if (vst[i] == -1)ans = (ans + 1) % mod;
    cout << (ans + 1) % mod << '\n';
    for (int i = 1; i <= n; i ++) vi[i].clear();
    for (int i = 1; i <= m; i ++) vst[i] = -1;
}

int main()
{
    ios::sync_with_stdio(0); cin.tie(0);
    int T = 1;
    // cin >> T;
    while (cin >> n >> m) sol();
    return 0;
}