#include <bits/stdc++.h>

#define NMAX 100010
using namespace std;

class Task {
	
public:
  void solve() {
    read_input();
    get_result();
    print_output();
  }
	
private:
  int n, maxim;
  int sol[NMAX];
  vector<int> adj[NMAX];
  queue<int> q;
	
  void read_input() {
      fstream in("darb.in");
      in >> n;
	
      for (int i = 1; i <= n; ++i) {
        int x, y;
        in >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
      }
      in.close();
  }

  void bfs(int s) {
      int i, j, k;
      for(i = 1; i <= n; ++i)
      sol[i] = -1;
      sol[s] = 0;
      q.push(s);

      while(!q.empty()) {
        i = q.front();
        q.pop();
	
        for(k = 0; k < adj[i].size(); ++k) {
            j = adj[i][k];
            if(sol[j] == -1) {
                sol[j] = 1 + sol[i];
                q.push(j);
            }
        }
      }
  }

  void get_result() {
      int node, i;
      bfs(1);

      maxim = 0;
      for(i = 1; i <= n; ++i)
        if(sol[i] > maxim) {
            maxim = sol[i];
            node = i;
        }

      bfs(node);
      for(i = 1; i <= n; ++i)
        maxim = max(maxim, sol[i]);
      maxim++;
  }

  void print_output() {
      ofstream out("darb.out");
      out << maxim << endl;
      out.close();
  }
};

int main() {
  Task *task = new Task();
  task->solve();
  delete task;

  return 0;
}