#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <string>
#include <set>
#include <algorithm>
using namespace std;
int a[2000][2],b,c,d,l,m,n,s;
void DFS(int k)
{
	if (k==0)
	{
		if (c>s) s=c;
		c--;
		return;
	}
	c++;
	DFS(a[k][0]);
	c++;
	DFS(a[k][1]);
	c--;
}
int main(void)
{
	freopen ("stroll.in","r",stdin);
	freopen ("stroll.out","w",stdout);
	scanf("%d",&b);
	for (c=0;c<b;c++)
	{
		scanf("%d%d%d",&l,&m,&n);
		a[l][0]=m;
		a[l][1]=n;
	}
	c=0;
	DFS(1);
	printf("%d",s);
	fclose(stdin);
	fclose(stdout);
	return 0;
}