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

vector<vector<int>> graph = vector<vector<int>>(600001, vector<int>());
vector<int> needed = vector<int>(600001, 0);

void dfs(int node) {
  if (graph[node].size() == 0) {
    needed[node] = 1;
    return;
  }
  int ans = 0;
  for (auto son : graph[node]) {
    dfs(son);
    ans += needed[son];
  }
  needed[node] = ans;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int k, n;
  cin >> k >> n;
  vector<vector<int>> days = vector<vector<int>>(k, vector<int>());
  int cnt = 1;
  for (int i = 0; i < n; i++) {
    days[0].push_back(cnt);
    cnt++;
  }
  for (int i = 1; i < k; i++) {
    int d;
    cin >> d;
    for (int j = 0; j < d; j++) {
      int x;
      cin >> x;
      if (x != 0) {
        int parent = days[i - 1][x - 1];
        graph[parent].push_back(cnt);
      }
      days[i].push_back(cnt);
      cnt++;
    }
  }
  int ans = 0;
  for (int i = 0; i < k; i++) {
    int req = 0;
    for (int j = 0; j < days[i].size(); j++) {
      int node = days[i][j];
      if (needed[node] == 0) {
        dfs(node);
      }
      req += needed[node];
    }
    ans = max(ans, req);
  }
  cout << ans;
}