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

void solve() {
	int k, n1; cin >> k >> n1;
	vector<vector<int> > nxt(k + 1), id(k + 1);
	nxt[0].resize(n1 + 1); id[0].resize(n1 + 1);
	int tot = 0;
	for(int i = 1; i <= n1; i++) id[0][i] = ++tot;
	for(int i = 1; i <= k; i++) {
		int l; cin >> l;
		nxt[i].resize(l + 1), id[i].resize(l + 1);
		for(int j = 1; j <= l; j++) cin >> nxt[i][j];
		for(int j = 1; j <= l; j++) id[i][j] = ++tot;
	}
	vector<vector<int> > G(tot + 1); vector<int> in(tot + 1), f(tot + 1);
	for(int i = 1; i <= k; i++) {
		int l = nxt[i].size() - 1;
		for(int j = 1; j <= l; j++)
			G[id[i][j]].push_back(id[i - 1][nxt[i][j]]), in[id[i - 1][nxt[i][j]]]++;
	} queue<int> q;
	for(int i = 1; i <= tot; i++)
		if(!in[i]) f[i] = 1, q.push(i);
	while(!q.empty()) {
		int u = q.front(); q.pop();
		for(auto v : G[u]) {
			f[v] += f[u];
			if(!--in[v]) q.push(v);
		}
	} int ans = 0;
	for(int i = 0; i <= k; i++) {
		int l = nxt[i].size() - 1;
		int sum = 0;
		for(int j = 1; j <= l; j++)
			sum += f[id[i][j]];
		ans = max(ans, sum);
	} cout << ans << '\n';
}

signed main() {
	ios::sync_with_stdio(false);
	ios_base::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	// For Problem with file IO
	// #ifndef CPH
	//   freopen(".in", "r", stdin);
	//   freopen(".out", "w", stdout);
	// #endif
	int t = 1;
	// cin >> t;
	while(t--) {
		solve();
	}
	return 0;
}