#include <iostream>
#include <vector>
#include <queue>
#include <fstream>
#include <algorithm>

using namespace std;

ifstream f("darb.in");
ofstream g("darb.out");

const int NMAX = 100005;
vector<int> adj[NMAX];
int dist[NMAX];
int n;

int bfs(int st)
{
    for (int i = 1; i <= n; i++)
        dist[i] = -1;

    queue<int> q;
    q.push(st);
    dist[st] = 1;

    int st2 = st;

    while (!q.empty())
    {
        int u = q.front();
        q.pop();
        if (dist[u] > dist[st2])
        {
            st2 = u;
        }

        for (int v : adj[u])
        {
            if (dist[v] == -1)
            {
                dist[v] = dist[u] + 1;
                q.push(v);
            }
        }
    }

    return st2;
}

int main()
{
    f>>n;
    for (int i = 0; i < n - 1; i++)
    {
        int u, v;
        f >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    int x = bfs(1);
    int y = bfs(x);

    g << dist[y] << endl;

    return 0;
}