#include<bits/stdc++.h> using namespace std; int a[10000],ma; int main(){ int n; cin>>n; a[1]=1; for(int i=1;i<=n;i++){ int x,y,m; cin>>x>>y; if(x==0&&y==0) continue; a[x]=a[i]+1; a[y]=a[y]+1; m=max(a[x],a[y]); if(i==1||ma<m) ma=m; } cout<<ma; }