#include<bits/stdc++.h>
using namespace std;
const int N=1e6+5;
int n,m,cnt;
int rd0[N],rd1[N];
vector<int> pic[N];
queue<int> q;
void topo_sort();
int main(){
	int v;
	cin>>n;
	for(int i=1;i<=n;i++){
		while(cin>>v&&v!=0){
			pic[v].push_back(i);
			rd0[i]++;
		}
	}
	for(int i=1;i<=n;i++){
		//cout<<rd0[i]<<endl;
		for(int j=1;j<=n;j++){
			rd1[j]=rd0[j];
		}
		q.push(i);
		topo_sort(); 
	}
	return 0;
}
void topo_sort(){
	cnt=0;
	while(!q.empty()){
		int x=q.front();
		q.pop();
		int len=pic[x].size();
		for(int i=0;i<len;i++){
			int Next=pic[x][i];
			rd1[Next]--;
			if(rd1[Next]==0){
				q.push(Next);
				cnt++;
			}
		}
	}
	cout<<cnt<<endl;
	return;
}