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

#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define x first
#define y second
#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)

typedef long long ll;
typedef double db;
typedef long double LD;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<db, db> pdd;

#ifdef ONPC
mt19937 rnd(228);
#endif


struct DSU
{
	vector<int> p;
	vector<int> S;

	DSU(int n)
	{
		p = vector<int>(n);
		iota(all(p),0);
		S = vector<int>(n, 1);
	}
	
	int find(int v)
	{
		if(v==p[v])
			return v;
		return p[v] = find(p[v]);
	}
	int get_sz(int v)
	{
		v = find(v);
		return S[v];
	}
	void unite(int a, int b)
	{
		a = find(a);
		b = find(b);
		if(a != b)
		{
			S[b] += S[a];
			p[a] = b;
			S[a] = 0;
		}
	}
};

int solve()
{
	int m, n;
	if (!(cin >> m >> n))
		return 1;
	
	vector<pii> ps(n, {-1, -1});
	// m - len of vector
	FOR(i,0,m)
	{
		int k;
		cin >> k;
		
		FOR(_,0,k)
		{
			int el;
			cin >> el;
			--el;
			if(ps[el].x == -1)
				ps[el].x = i;
			else
				ps[el].y = i;
		}
	}

	int rank = 0;
	auto dsu = DSU(m);
	for(auto [x, y]: ps)
	{
		assert(!(x == -1 || y == -1));
		if(dsu.find(x) != dsu.find(y))
		{
			dsu.unite(x, y);
			rank = max(rank, dsu.get_sz(x)-1);
		}
	}
	cout << rank << '\n';
	return 0;	
}

int32_t main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int TET = 1e9;
	//cin >> TET;
	for (int i = 1; i <= TET; i++)
	{
		if (solve())
			break;
			
		#ifdef ONPC
			cerr << "_________________________________\n";
		#endif
	}
	#ifdef ONPC
		cerr << "\nfinished in " << clock() * 1.0 / CLOCKS_PER_SEC << " sec\n";
	#endif
	return 0;
}