#include <bits/stdc++.h>
using namespace std;

class Task {
   public:
    void solve() {
        read_input();
        print_output(get_result());
    }

   private:
    // numarul maxim de noduri
    static constexpr int NMAX = (int)1e5 + 5;  // 10^5 + 5 = 100.005

    // n = numar de noduri, m = numar de muchii/arce
    int n, m;

    // adj[node] = lista de adiacenta a nodului node
    // exemplu: daca adj[node] = {..., neigh, ...} => exista muchia (node, neigh)
    vector<int> adj[NMAX];

    // nodul sursa in parcurgerea BFS

    void read_input() {
        ifstream fin("darb.in");
        fin >> n;
        for (int i = 1, x, y; i < n; i++) {
            fin >> x >> y;  // muchie (x, y)
            adj[x].push_back(y);
            adj[y].push_back(x);
        }
        fin.close();
    }

    int get_result() {
        // TODO: Faceti un BFS care sa construiasca in d valorile cerute:
        // * d[node] = numarul minim de muchii de parcurs de la nodul `source` la nodul `node`
        //      * d[source] = 0
        //      * d[node]   = -1, daca nu exista drum de la source la node
        // *******
        // ATENTIE: nodurile sunt indexate de la 1 la n.
        // *******

        vector<int>d(n+1,INT32_MAX);
        int source=1,maxi=-1;
        int last_node;
        d[source]=0;
        queue<int>q;
        q.push(source);

        while(!q.empty()){
            int node=q.front();
            last_node=node;
            q.pop();

            for(auto &neight:adj[node]){
                if(d[neight]==INT32_MAX){
                    d[neight]=d[node]+1;
                    q.push(neight);
                }
            }
        }

        for(int i=1;i<=n;i++)
            d[i]=INT32_MAX;
        

        d[last_node]=0;
    
        q.push(last_node);

        while(!q.empty()){
            int node=q.front();
            last_node=node;
            q.pop();

            for(auto &neight:adj[node]){
                if(d[neight]==INT32_MAX){
                    d[neight]=d[node]+1;
                    q.push(neight);
                }
            }
        }

        

        for(int i=1;i<=n;i++)
            if(d[i]!=INT32_MAX && maxi<d[i])
                maxi=d[i];
        return maxi+1;
    }

    void print_output(int d) {
        ofstream fout("darb.out");
        fout << d << '\n';
        fout.close();
    }
};

// [ATENTIE] NU modifica functia main!
int main() {
    // * se aloca un obiect Task pe heap
    // (se presupune ca e prea mare pentru a fi alocat pe stiva)
    // * se apeleaza metoda solve()
    // (citire, rezolvare, printare)
    // * se distruge obiectul si se elibereaza memoria
    auto* task = new (nothrow) Task();  // hint: cppreference/nothrow
    if (!task) {
        cerr << "new failed: WTF are you doing? Throw your PC!\n";
        return -1;
    }
    task->solve();
    delete task;
    return 0;
}