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

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

private:
    static constexpr int NMAX = (int)1e5 + 5;
    int n;

    vector<int> adj[NMAX];

    void read_input() {
        ifstream fin("darb.in");
        fin >> n;
        int x, y;
        while (fin >> x >> y) {
            adj[x].push_back(y);
            adj[y].push_back(x);
        }
        fin.close();
    }

    vector<int> get_result() {

        vector<int> d1(n + 1, -1);
        vector<int> d2(n + 1, -1);
        vector<int> visited(n + 1);
        int source = 1;

        d1[source] = 1;
        visited[source] = 1;

        queue<int> q;
        q.push(source);

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

            for(auto neigh : adj[node]) {
                if(visited[neigh] == 0) {
                    q.push(neigh);
                    d1[neigh] = d1[node] + 1;
                    visited[neigh] = 1;
                }
            }
        }
        int maxi = -1;
        int max_leaf;

        for(int i = 1; i <= n; i++) {
            if (d1[i] > maxi) {
                maxi = d1[i];
                max_leaf = i;
            }
            visited[i] = 0;
        }

        source = max_leaf;
        d2[source] = 1;
        visited[source] = 1;

        q.push(source);

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

            for(auto neigh : adj[node]) {
                if(visited[neigh] == 0) {
                    q.push(neigh);
                    d2[neigh] = d2[node] + 1;
                    visited[neigh] = 1;
                }
            }
        }

        return d2;
    }

    void print_output(const vector<int>& d) {
        ofstream fout("darb.out");
        int maxi = -1;
        for (int node = 1; node <= n; node++) {
            if (maxi < d[node]) {
                maxi = d[node];
            }
        }
        fout << maxi;
        fout.close();
    }
};

int main() {
    auto* task = new (nothrow) Task();
    if (!task) {
        cerr << "new failed: WTF are you doing? Throw your PC!\n";
        return -1;
    }
    task->solve();
    delete task;
    return 0;
}