teamup

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#define task ""

using namespace std;
using ll = long long;

const int N = 3e5 + 2;
vector<int> f[N], s[N], cnt[N];
vector<int> adj[N];
int a[N], id[N], par[N];
int m, n, p;

void Read(){
    cin >> n >> m >> p;
    for (int i = 1; i <= m; ++i){
        int v;
        cin >> v;
        s[i].resize(v);
        for(auto &j : s[i])
            cin >> j;
        id[i] = i;
    }
    for (int i = 1; i <= p; ++i){
        cin >> a[i];
        cnt[a[i]].push_back(i);
    }
    sort(id + 1, id + m + 1, [&](const int &x, const int &y) {
        return s[x].size() < s[y].size();
    });
    for (int i = 1; i <= m; ++i)
        for (auto j : s[id[i]])
            f[j].push_back(id[i]);
}

inline void Unique(vector<int> &s){
    sort(s.begin(), s.end());
    s.resize(unique(s.begin(), s.end()) - s.begin());
}

bool Check(vector<int> ans){
    vector<int> v;
    for(auto i : ans)
        for(auto j : s[i])
            v.push_back(j);
    Unique(v);
    return v.size() == n;
}

void BuildDAG(){
    for (int i = 1; i <= n; ++i)
        for(auto j : f[i]){
            int l = 0, m, h = (int)f[i].size() - 1;
            while(l <= h){
                m = (l + h) / 2;
                if(s[f[i][m]].size() <= s[j].size())
                    l = m + 1;
                else
                    h = m - 1;
            }
            if(l < f[i].size()){
                par[j] = f[i][l];
                adj[f[i][l]].push_back(j);
            }
        }
    //for (int i = 1; i <= m; ++i)
    //    cout << i << ": " << a[i] << "\n";
}

void Solve(){
    vector<int> ans;
    vector<vector<int>> res;
    int num(0);
    for (int i = 1; i <= m; ++i){
        Unique(adj[i]);
        if(par[i] == 0 && cnt[i].size() != 0){
            num += s[i].size();
            ans.push_back(i);
        }
    }
    do{
        if(num != n)
            break;
        vector<int> tmp, now;
        for(auto i : ans){
            now.push_back(cnt[i].back());
            cnt[i].pop_back();
            if(cnt[i].empty()){
                tmp.push_back(i);
                num -= s[i].size();
            }
        }
        res.push_back(now);
        for (int i = (int)ans.size() - 1; ~i; --i)
            if(cnt[ans[i]].empty()){
                ans[i] = ans.back();
                ans.pop_back();
            }
        for(auto i : tmp)
            for(auto j : adj[i])
                if(cnt[j].size()){
                    ans.push_back(j);
                    num += s[j].size();
                }
    } while (ans.size());
    cout << res.size() << "\n";
    for(auto i : res){
        cout << i.size() << " ";
        for(auto j : i)
            cout << j << " ";
        cout << "\n";
    }
}

int32_t main(){
    if(fopen(task".INP", "r")){
        freopen(task".INP", "r", stdin);
    freopen(task".OUT", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    Read();
    BuildDAG();
    Solve();
}