#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

const int NMAX = 100001;

int N, ult, dist[NMAX];
bool viz[NMAX];
vector<int> lista[NMAX];
queue<int> coada;

void citire()
{
    int x, y;
    f >> N;

    for(int i = 1; i < N; i++)
    {
        f >> x >> y;
        lista[x].push_back(y);
        lista[y].push_back(x);
    }
}

void BFS(int x)
{
    viz[x] = 1;
    dist[x] = 1;
    coada.push(x);
    ult = x;
    while(!coada.empty())
    {
        int crt = coada.front();
        coada.pop();
        for(auto it : lista[crt])
        {
            if(viz[it] == 0)
            {
                coada.push(it);
                dist[it] = dist[crt] + 1;
                viz[it] = 1;
                ult = it;
            }
        }
    }
}
int main()
{
    citire();
    BFS(1);
    for(int i = 1; i <= N; i++)
    {
        viz[i] = 0;
        dist[i] = 0;
    }
    BFS(ult);
    g << dist[ult];
    f.close();
    g.close();
    return 0;
}