#include<bits/stdc++.h>

using namespace std;

const int MAX = 500005;

vector <int> G[MAX];
int suma[MAX];
int deg[MAX];
int T[MAX];

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

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

    int ost=n;
    int r=n;

    int a, x;

    for (int i=1; i<=n; i++) deg[i] = 1;

    for (int dzien=2; dzien<=k; dzien++){
        cin >> a;
        for (int i=1; i<=a; i++){
            cin >> x;
            r++;
            deg[r] = dzien;
            if (x != 0){
                G[r-i-ost+x].push_back(r);
            }
        }
        ost = a;
    }

    int wyn = n;

    for (int i=r; i>=1; i--){
        int s=0;
        for (int j : G[i]){
            s += T[j];
        }
        if (s == 0) T[i] = 1;
        else T[i] = s;
        suma[deg[i]] += T[i];
    }

    for (int i=1; i<=k; i++){
        wyn = max(wyn, suma[i]);
    }

    cout << wyn << "\n";

    return 0;
}