#include <bits/stdc++.h>
#include <ctime>
using namespace std;

#define pb push_back
#define f first
#define s second
#define mp make_pair
#define ll long long

#define MAXN 200005
#define INF 1000000009
#define MOD 1000000007


list < set < int > > kerbosh(vector < vector <bool> > a,int SIZE){
    set <int> M,G,K,P;
    list<set<int> > REZULT;
    for (int i=0; i<SIZE;i++)
    {
        K.insert(i);
    }
    int v,Count=0,cnt=0;
    int Stack1[100];
    std::set<int> Stack2[100];
    std::set<int>::iterator theIterator;
    theIterator=K.begin();

    auto t = clock();
    auto pre = t;
    while ((K.size()!=0)||(M.size()!=0))
    {
    	if(clock() - t > 10000000){
    		cerr << (clock() - t) / 1000000 << " " << (clock() - pre) / 1000000 << " " << v << endl;
    		t = clock();
    		if(clock() - pre > 1000000 * 20)
    			return REZULT;
    	}

        if (K.size()!=0)
        {
            theIterator=K.begin();
            v=*theIterator;
            Stack2[++Count]=M;
            Stack2[++Count]=K;
            Stack2[++Count]=P;
            Stack1[++cnt]=v;
            M.insert(v);
            for (int i=0;i<SIZE;i++)
            {
                if (a[v][i])
                {
                    theIterator=K.find(i);
                    if (theIterator!=K.end())
                    {
                        K.erase(theIterator);
                    }
                    theIterator=P.find(i);
                    if (theIterator!=P.end())
                    {
                        P.erase(theIterator);
                    }
                }
            }
            theIterator=K.find(v);
            if (theIterator!=K.end())
            {
                K.erase(theIterator);
            }
        }
        else
        {
            if (P.size()==0)
            {
                REZULT.push_back(M);
            }
            v=Stack1[cnt--];
            P=Stack2[Count--];
            K=Stack2[Count--];
            M=Stack2[Count--];
            theIterator=K.find(v);
            if (theIterator!=K.end())
            {
                K.erase(theIterator);
            }
            P.insert(v);
        }
    }
    return  REZULT;
 }

void solve(){
	vector < vector <int> > gr;
	int n, m; // число аудиторий, число мероприятий
	cin >> n >> m;

	vector <vector <int>> v;
	v.resize(m);
	for(int i = 0; i < m; i++){
		int c;
		cin >> c;
		for(int j = 0; j < c; j++){
			int a;
			cin >> a;
			v[i].pb(a);
		}
	}

	gr.clear();
	gr.resize(m+1);

	for(int i = 0; i < m; i++){
		cerr << i << " ";
		for(int j = i+1; j < m; j++){
			set <int> a;
			for(auto x: v[i])
				a.insert(x);

			bool y = 1;
			for(auto x: v[j])
				if(a.find(x) != a.end())
					y = 0;

			if(y){
				gr[i+1].pb(j+1);
				gr[j+1].pb(i+1);
			}
		}
	}

	cerr << endl << gr.size() << " gr:\n";
	for(int i = 0; i < gr.size(); i++){
		cerr << i << ": ";
		for(auto x: gr[i])
			cerr << x << " ";
		cerr << endl;
	}
	cerr << endl;

	vector < vector < bool > > g;
	g.resize(gr.size());
	for(int i = 0; i < gr.size(); i++){
		g[i].resize(gr.size(), 1);
		cerr << i << ": ";
		for(auto x: gr[i]){
			g[i][x] = 0;
			cerr << x << " ";
		}
		cerr << endl;
	}

	cerr << "matrix: \n";
	for(int i = 0; i < gr.size(); i++){
		for(int j = 0; j < gr.size(); j++)
			cerr << g[i][j] << " ";
		cerr << endl;
	}
	cerr << endl;

	auto ans = kerbosh(g, (int)g.size());
	cerr << "ans: \n";
	vector < set <int> > mx;
	set <int> j;
	mx.pb(j);
	while(!ans.empty()){
		auto out = *(ans.rbegin());
		ans.pop_back();

		cerr << out.size() << ": ";
		for(auto x: out)
			cerr << x << " ";

		if(out.size() >= mx[0].size()){
			if(out.size() > mx[0].size()) mx.clear();
			mx.pb(out);
		}
		cerr << endl;
	}
	cerr << endl;


	cerr << "MX.SIZE = " <<  mx.size() << endl;
	int mx_a = 0;
	set <int> out;
	for(auto x: mx){
		int a = 0;
		for(auto s: x){
			a+= v[s-1].size();
		}
		if(a > mx_a){
			mx_a = a;
			out = x;
		}
	}

	cout << out.size() << endl;
	for(auto x: out)
		cout << x << " ";
	cout << endl;
}

int main(){
	ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

	int tests = 1;

#ifdef LOCAL
	bool a;
	a = freopen("in.data", "r", stdin);
	a = freopen("out.data", "w", stdout);
	cin >> tests;
#endif

	for(int i = 1; i <= tests; i++){
		cerr << "TEST " << i << endl;
		solve();
	}

	cerr << "End of program";

	return 0;
}