采用拓扑排序，

#include <iostream>
#include <queue>
using namespace std;

static int head[10001], nxt[10001], to[10001], stop[1001];
static int indegree[10001], ans[10001], cnt = 1;
static void add_edge(int u, int v)
{
	nxt[cnt] = head[u];
	to[cnt] = v;
	head[u] = cnt++;
}

static void topu(int n)
{
	queue<int> buf;

	for (int i = 1; i <= n; ++i)
		if (!indegree[i]) buf.emplace(i),ans[i] = 1;

	while (!buf.empty())
	{
		auto fr = buf.front();
		buf.pop();

		for (int ei = head[fr]; ei; ei = nxt[ei])
		{
			auto dest = to[ei];
			ans[dest] = max(ans[dest], ans[fr] + 1);
			indegree[dest]--;
			if (!indegree[dest]) buf.emplace(dest);
		}
	}
}

int main()
{
	int n, m;
	cin >> n >> m;

	for (int i = 0; i < m; ++i)
	{
		int num;
		cin >> num;

		memset(stop, false, sizeof stop);
		for (int c = 1; c <= num; ++c)
		{
			int d;
			cin >> d;
			stop[d] = true;
		}

		vector<int> ust, st;
		for (int i = 1; i <= num; ++i)
		{
			if (!stop[i]) ust.emplace_back(i);
			else st.emplace_back(i);
		}

		for (auto u : ust)
			for (auto v : st)
				add_edge(u, v), indegree[v]++;
	}

	topu(n);

	int maxn = 1;
	for (int i = 1; i <= n; ++i)
		maxn = max(maxn, ans[i]);
	cout << maxn << endl;
}