#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];

    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); // graf neorientat
        }
        fin.close();
    }

    int bfs_getLast(int source) {
        queue<int> q;
        set<int> visited;
        int node = 1;
        q.push(source);
        visited.insert(source);

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

            for (int neigh : adj[node]) {
                // cout << "Neigh: " << neigh << ' ';
                if (visited.find(neigh) == visited.end()) {
                    q.push(neigh);
                    visited.insert(neigh);
                    // cout << "Last: " << last << '\n';
                }
            }
        }

        return node;
    }

    int bfs_getMaxDist(int source) {
        int d = 0;
        queue<int> q;
        set<int> visited;
        q.push(source);

        while (!q.empty()) {
            queue<int> q_aux;
            d++;

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

                for (int neigh : adj[node]) {
                    if (visited.find(neigh) == visited.end()) {
                        q_aux.push(neigh);
                        visited.insert(neigh);
                    }
                }
            }

            q = q_aux;
        }

        return d;
    }

    int get_result() {
        int last = bfs_getLast(1);
        // cout << "Last_end: " << last << '\n';

        return bfs_getMaxDist(last);
    }

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

int main() {
    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;
}