#include <iostream>
#include <vector>

using namespace std;

typedef unsigned long long ull;

ull sum(const vector<ull> &v) {
    ull sum = 0;
    for (size_t i = 1; i < v.size(); i++) {
        sum += v[i];
    }
    return sum;
}

int main() {
    ios_base::sync_with_stdio(false);

    auto conferences_by_day = vector<int>();

    int k, n, a;
    cin >> k >> n;

    vector<vector<ull> > meetings(k + 1);
    vector<vector<ull> > results(k + 1);

    meetings[0].resize(1);
    results[0].resize(1);
    meetings[1].resize(n + 1);
    results[1].resize(n + 1);

    for (int i = 2; i <= k; i++) {
        cin >> a;
        meetings[i].resize(a + 1);
        results[i].resize(a + 1);
        for (int j = 1; j <= a; j++) {
            cin >> meetings[i][j];
        }
    }

    for (int i = k; i >= 1; i--) {
        for (int j = 1; j < results[i].size(); j++) {
            if (results[i][j] == 0) {
                results[i][j] = 1;
            }
            if (meetings[i][j] != 0) {
                results[i - 1][meetings[i][j]] = results[i - 1][meetings[i][j]] + results[i][j];
            }
        }
    }

    ull m = 0;
    for (int i = 1; i <= k; i++) {
        if (const auto s = sum(results[i]); s > m) {
            m = s;
        }
    }
    cout << m << "\n";

    return 0;
}