#include<iostream> #include<algorithm> using namespace std; int a[128], n, b[128], r; void f(int n,int x) { if (a[n]) f(a[n], x + 1); if (b[n]) f(b[n], x + 1); if (!a[n] && !b[n]) r = max(r, x); } int main() { cin >> n; for (int i{ 1 }; i <= n; i++) cin >> a[i] >> b[i]; f(1, 1); cout << r; return 0; }