#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
int n,q[1005][2]={0};
bool used[1005]={0};
int answer=1;
int tmp=1;
void dfs(int x);
int main()
{
	freopen ("stroll.in","r",stdin);
	freopen ("stroll.out","w",stdout);
	cin>>n;
	for (int i=0;i<n;i++)
	{
		int a,b,c;
		cin>>a>>b>>c;
		q[a][0]=b;
		q[a][1]=c;
	}
	dfs(1);
	cout<<answer;
}
void dfs(int x)
{
	if (tmp>answer)
		answer=tmp;
	for (int i=0;i<2;i++)
	{
		if (q[x][i]!=0)
		{
			tmp++;
			dfs(q[x][i]);
			tmp--;
		}
	}
}