#include <bits/stdc++.h>
using namespace std;
bitset<50001> G[50001], cur, all;
vector<vector<int>> C[11];
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, k, sz, u, v; cin >> n >> k;
for (int i = 0; i < n; ++i) C[1].push_back({i}), G[i][i] = 1, all[i] = 1;
for (u = 0; u < n; ++u) {
cin >> sz;
while (sz--) cin >> v, G[u][v] = 1;
}
vector<int> tmp;
for (sz = 2; sz <= k; ++sz) {
for (auto small_clique : C[sz - 1]) {
cur = all;
for (int i : small_clique) cur &= G[i];
for (int j = small_clique.back() + 1; j < n; ++j) if (cur[j]) {
tmp = small_clique; tmp.push_back(j);
C[sz].push_back(tmp);
}
}
if (C[sz].empty()) {cout << sz - 1; return 0;}
// cout << sz << "!!" << '\n';
// for (auto clique : C[sz]) {
// for (int i : clique) cout << i << ' ';
// cout << '\n';
// }
}
cout << k;
}
