#include <fstream>
#include <queue>
#include <vector>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
vector <int> L[100005];
queue <int> q;
int n, sf, dist[100005], diametru;
bool viz[100005];
void citire();
void bfs(int start);
void afisare();

int main()
{
    citire();
    bfs(1);
    bfs(sf);
    afisare();
    return 0;
}

void citire()
{
    int i, x, y;
    fin >> n;
    for (i = 1; i < n; i++)
    {
        fin >> x >> y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
}

void bfs(int start)
{
    int nod, i;
    q.push(start);
    dist[start] = 1;
    if(start==1)
    {
        while (!q.empty())
        {
            nod = q.front();
            q.pop();
            for (i = 0; i < L[nod].size(); i++)
                if (!viz[L[nod][i]])
                {
                    q.push(L[nod][i]);
                    viz[L[nod][i]] = true;
                    dist[L[nod][i]] = dist[nod] + 1;
                    diametru = dist[L[nod][i]];
                }
        }
        sf = nod;
    }
    else
        while (!q.empty())
        {
            nod = q.front();
            q.pop();
            for (i = 0; i < L[nod].size(); i++)
                if (viz[L[nod][i]])
                {
                    q.push(L[nod][i]);
                    viz[L[nod][i]] = false;
                    dist[L[nod][i]] = dist[nod] + 1;
                    diametru = dist[L[nod][i]];
                }
        }
    sf = nod;
}

void afisare()
{
    fout << diametru << '\n';
}