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

ifstream fin("darb.in");
ofstream fout("darb.out");

int bfs(vector<vector<int>>& graph, int start, vector<int>& distances) {
    int n = graph.size();
    vector<bool> visited(n + 1, false);
    queue<int> q;
    q.push(start);
    visited[start] = true;
    int lastVisited = start;
    while (!q.empty()) {
        int node = q.front();
        q.pop();
        for (int neighbor : graph[node]) {
            if (!visited[neighbor]) {
                visited[neighbor] = true;
                distances[neighbor] = distances[node] + 1;
                q.push(neighbor);
                lastVisited = neighbor;
            }
        }
    }
    return lastVisited;
}

int main() {
    int n;
    fin >> n;
    vector<vector<int>> graph(n + 1);
    for (int i = 0; i < n - 1; ++i) {
        int x, y;
        fin >> x >> y;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    vector<int> distances(n + 1, 1);
    int firstEnd = bfs(graph, 1, distances);
    fill(distances.begin(), distances.end(), 1);
    int secondEnd = bfs(graph, firstEnd, distances);
    fout << distances[secondEnd];
    return 0;
}