#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream is ("darb.in");
ofstream os ("darb.out");

vector <int> v[100004], d;
queue <int> Q;
int N, D, poz;
void Read();
void BFS();
int main()
{
    Read();
    Q.push(1);
    d[1] = 1;
    BFS();
    for(int i = 1; i <= N; ++i)
        d[i] = 0;
    Q.push(poz);
    d[poz] = 1;
    BFS();
    os << d[poz];
    return 0;
}
void Read()
{
    int x, y;
    is >> N;
    d.resize(N+1);
    for(int i = 1; i < N; ++i)
    {
        is >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}
void BFS()
{
    vector<int>::iterator it;
    int nod;
    while(!Q.empty())
    {
        nod = Q.front();
        Q.pop();
        for(it = v[nod].begin(); it != v[nod].end(); ++it)
            if(!d[*it])
            {
                d[*it] = d[nod]+1;
                if(d[*it] > D)
                {
                    D = d[*it];
                    poz = *it;
                }
                Q.push(*it);
            }
    }
}