// iostream is too mainstream
#include <cstdio>
// bitch please
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <cmath>
#include <iomanip>
#define dibs reserve
#define OVER9000 1234567890
#define ALL_THE(CAKE,LIE) for(auto LIE =CAKE.begin(); LIE != CAKE.end(); LIE++)
#define tisic 47
#define soclose 1e-8
#define chocolate win
// so much chocolate
#define patkan 9
#define ff first
#define ss second
#define abs(x) ((x < 0)?-(x):x)
#define uint unsigned int
#define dbl long double
using namespace std;
// mylittledoge

int main() {
	cin.sync_with_stdio(0);
	cin.tie(0);
	string s;
	map<string,int> M;
	vector< vector<int> > dep;
	vector<int> name;
	vector<int> akt;
	while(cin >> s) {
		if(s == "0") {
			dep.push_back(akt);
			akt.clear();}
		else {
			int x =(M.find(s) == M.end())?M.size():M[s];
			M[s] =x;
			if(name.size() == dep.size()) name.push_back(x);
			else akt.push_back(x);}
		}
	int N =M.size();
	vector< vector<int> > G(N);
	vector<int> D(N,-OVER9000);
	for(int i =0; i < name.size(); i++) D[name[i]] =0;
	for(int i =0; i < dep.size(); i++) ALL_THE(dep[i],it) {
		G[*it].push_back(name[i]);
		D[name[i]]++;}

	queue<int> q;
	for(int i =0; i < N; i++) if(D[i] == 0) q.push(i);

	int ans =0;
	while(!q.empty()) {
		ans++;
		int a =q.front();
		ALL_THE(G[a],it) {
			D[*it]--;
			if(D[*it] == 0) q.push(*it);}
		q.pop();}

	cout << ans << "\n";
	return 0;}

// look at my code
// my code is amazing