#include <bits/stdc++.h> using namespace std; int n,ans=-0x3f3f3f3f; struct node{ int left,right; }tree[1000005]; void dfs(int p, int deep) { if(p == 0)return; ans = max(ans,deep); dfs(tree[p].left,deep+1); dfs(tree[p].right,deep+1); } signed main() { cin >> n; for(int i = 1; i <= n; i++)cin>>tree[i].left>>tree[i].right; dfs(1,1); cout << ans << endl; return 0; }