rt

#include<bits/stdc++.h>
#define endl "\n"
#define mp make_pair
#define int long long
#define ull unsigned long long
using namespace std;
const long long mod=1000000001;
const long long P=201;
int n,m;
struct node{
	map<int,int>c;
	int x;
}a[2000001];
vector<int>b[2000001];
int fa[2000001];
int dfs(int x)
{
	int ans=0;
	for(int i=0;i<b[x].size();i++)
	{
		ans+=dfs(b[x][i]);
	}
	int k=-1,cnt=1;
	for(auto y:a[x].c)
	{
		if(k==-1)k=y.second;
		if(k!=y.second)cnt=0;
		a[fa[x]].c[y.first]+=y.second;
	}
	return cnt+ans;
	
}
signed main()
{
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(0);
//	freopen("ce.in","r",stdin);
//	freopen("ce.out","w",stdout);
	cin>>n;
	int c,f;
	for(int i=1;i<=n;i++)
	{
		cin>>c>>f;
		fa[i]=f;
		b[f].push_back(i);
		a[i].c[c]=1;
	}
	cout<<dfs(1)<<endl;
	return 0;
	exit(0);
}