#include <iostream>
#include <vector>
#include <unordered_map>

struct Day {
    std::vector<int> dependencies;
    Day(std::vector<int> _dependencies) : dependencies(_dependencies) {}
};

int main() {
    int k, conferences;
    std::cin >> k >> conferences;

    std::vector<Day> days;
    days.emplace_back(std::vector<int>(conferences, 0));
    for (int i = 1; i < k; i++) {
        int n;
        std::cin >> n;
        std::vector<int> deps(n);
        for (int j = 0; j < n; j++) {
            std::cin >> deps[j];
        }
        days.emplace_back(deps);
    }

    long long result = 0;
    std::unordered_map<int, long long> confs, next_confs;
    for (int i = k - 1; i >= 0; --i) {
        for (int j = 1; j <= days[i].dependencies.size(); j++) {
            confs[j] = std::max(confs[j], 1LL);
        }

        long long needed = 0;
        for (int j = 1; j <= days[i].dependencies.size(); j++) {
            needed += confs[j];
        }
        result = std::max(result, needed);

        for (int j = 0; j < days[i].dependencies.size(); j++) {
            if (days[i].dependencies[j] > 0) {
                next_confs[days[i].dependencies[j]] += confs[j + 1];
            }
        }

        confs.clear();
        for (auto const [k,v]: next_confs) {
            confs[k] = v;
        }
        next_confs.clear();
    }
    std::cout << result << '\n';
    return 0;
}