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//Krzysztof Pieprzak
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int,int> pii;
typedef pair<long long, long long> pll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;

#define Size(x) (int)x.size()
#define VAR(v,n) auto v = (n)
#define FOR(i,a,b) for(VAR(i,a); i < (b); ++i)
#define FORE(i,a,b) for(VAR(i,a); i <= (b); ++i)
#define FORREV(i,a,b) for(VAR(i,b); i >= (a); --i)
#define FORSTEP(i,a,b,step) for(VAR(i,a); i < (b); i += (step))
#define FOREACH(i,c) for(auto i : (c))
#define FOREACHS(i,c,n) for(VAR(i,&(c)[0]); i-(c)<(n); ++i)
#define ALL(x) x.begin(),x.end()
#define CLEAR(t) memset(t, 0, sizeof(t))
#define F first
#define S second
#define MP make_pair
#define PUB push_back
#define POB pop_back
#define pieprzu ios_base::sync_with_stdio(0);
#define debug_enabled true
#define debug(name) if(debug_enabled) cout << endl << name << endl; if(debug_enabled)

const int    INF = 1000000001;
const double EPS = 10e-9;

const int MAXN = 500000;

int meetingsToPrevMeetings[MAXN + 5];
int meetingsToDays[MAXN + 5];
vi daysToMeetings[MAXN + 5];

int meetingPpls[MAXN + 5];
int dayPpls[MAXN + 5];

void rob(int test) {
    int days, n, prevMeeting;
    scanf("%d %d", &days, &n);
    
    int meetingId = 1;
    FOR (i, 0, n) {
        daysToMeetings[0].PUB(meetingId);
        meetingsToDays[meetingId] = 0;
        ++meetingId;
    }
    
    FOR (day, 1, days) {
        scanf("%d", &n);
        FOR (i, 0, n) {
            scanf("%d", &prevMeeting);
            daysToMeetings[day].PUB(meetingId);
            meetingsToDays[meetingId] = day;
            
            if (prevMeeting != 0) {
                meetingsToPrevMeetings[meetingId] = daysToMeetings[day - 1][prevMeeting - 1];
            }
            
            ++meetingId;
        }
    }
    
    FORREV (i, 1, meetingId - 1) {
        int meetingPpl = max(1, meetingPpls[i]);
        dayPpls[meetingsToDays[i]] += meetingPpl;
        if (meetingsToPrevMeetings[i] != 0) {
            meetingPpls[meetingsToPrevMeetings[i]] += meetingPpl;
        }
    }
    
    int maxPpl = 0;
    FOR (i, 0, days) {
        maxPpl = max(maxPpl, dayPpls[i]);
    }
    
    printf("%d\n", maxPpl);
}

int main() {
    int test = 1;
    //scanf("%d", &test);

    FORE (i, 1, test) rob(i);

    return 0;
}