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#include <bits/stdc++.h>

using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())

template<class A, class B> auto &operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}

template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for (auto e : x) o << (", ")+2*!i++ << e;
    return o << '}';
}

#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n';
#else
#define debug(...) {}
#endif


constexpr int MAXN = 500'003;


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, k, m, x;
    cin >> k >> n;
    vector<vector<int>> conf(k);
    FOR(i, 1, k - 1) {
        cin >> m;
        REP(j, m) {
            cin >> x;
            conf[i].emplace_back(x);
        }
    }
    REP(i, n)
        conf[0].emplace_back(0);

    LL ans = 0;
    vector<LL> dp(MAXN), dp2(MAXN);
    for (int i = k - 1; i >= 0; i--) {
        m = ssize(conf[i]);
        LL needed = 0;
        FOR(j, 1, m) {
            dp[j] = max(dp[j], 1LL);
            needed += dp[j];
        }
        ans = max(ans, needed);

        FOR(j, 1, m) {
            auto prev = conf[i][j - 1];
            dp2[prev] += dp[j];
            dp[j] = 0;
        }

        swap(dp2, dp);
    }

    cout << ans << '\n';

    return 0;
}