#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
#define NMAX 100001

using namespace std;

vector < int > nod[NMAX];
queue < pair < int , int > > coada;

int N;
int diametru, aux;

bool viz[NMAX];

void Citire()
{
    ifstream fin("darb.in");
    int x, y;
    fin >> N;
    for (int i = 1;i < N;++i)
    {
        fin >> x >> y;
        nod[x].push_back(y);
        nod[y].push_back(x);
    }
    fin.close();
}

void Lee(int start)
{
    viz[start] = true; /// VIZITEZ POZITIA DE START
    coada.push(make_pair(start, 1)); /// POZITIA DE START SI NR DE PASI
    while (!coada.empty())
    {
        int nd = coada.front().first;
        int pasi = coada.front().second;
        coada.pop();
        if (pasi > diametru)
        {
            diametru = pasi;
            aux = nd;
        }
        for (int i = 0; i < nod[nd].size(); ++i)
            if (!viz[nod[nd][i]])
            {
                coada.push(make_pair(nod[nd][i], pasi + 1));
                viz[nod[nd][i]] = true;
            }
    }

}

int main()
{
    ofstream fout("darb.out");
    Citire();
    Lee(1);
    memset(viz, false , NMAX);
    diametru = 0;
    Lee(aux);
    fout << diametru;
    return 0;
}