#include<cstdio>

#include<iostream>

#include<set>

const int N=;

#define R register int

using namespace std;

inline int g() {

    R ret=; register char ch; while(!isdigit(ch=getchar()));

    do ret=ret*+(ch^); while(isdigit(ch=getchar())); return ret;

}

int n,m,cnt;

multiset<int>s[N];

int vr[N<<],nxt[N<<],fir[N],w[N];

inline void add(int u,int v) {vr[++cnt]=v,nxt[cnt]=fir[u],fir[u]=cnt;}

inline void dfs(int u) {

    for(R i=fir[u];i;i=nxt[i]) { R v=vr[i];

        dfs(v); if(s[u].size()<s[v].size()) swap(s[u],s[v]);

        for(multiset<int>::iterator it=s[v].begin();it!=s[v].end();++it) s[u].insert(*it);

    } multiset<int>::iterator it=s[u].lower_bound(w[u]); if(it!=s[u].end()) s[u].erase(it);

    s[u].insert(w[u]);

}

signed main() {

    n=g(); for(R i=,fa;i<=n;++i) {

        w[i]=g(),fa=g(); if(i==) continue; add(fa,i);

    } dfs(); printf("%d\n",s[].size());

}