#include <iostream>
#include<vector>
#include<fstream>
using namespace std;
void dfs(int nod,vector<int>& dist,vector<bool>& viz,const vector<vector<int> >& la )
{
    if(viz[nod])
        return;
    viz[nod]=true;
    for(int i=0; i<la[nod].size(); ++i)
        if(!viz[la[nod][i]])
        {
            dist[la[nod][i]]=dist[nod]+1;
            dfs(la[nod][i],dist,viz,la);
        }
}
int main()
{
    ifstream fin("darb.in");
    ofstream fout("darb.out");
    int n,x,y;
    fin>>n;
    vector<vector<int> > la;
    la.resize(n+1);
    for(int i=1; i<n; ++i)
    {
        fin>>x>>y;
        la[x].push_back(y);
        la[y].push_back(x);
    }
    vector<int> dist(n+1,1);
    vector<bool> viz(n+1,false);
    dfs(1,dist,viz,la);
    struct nod
    {
        int indice,distanta;
        nod(int x=0,int y=0):indice(x),distanta(y){}
    } maxim;
    for(int i=1; i<=n; ++i)
        if(maxim.distanta<dist[i])
        {
            maxim.indice=i;
            maxim.distanta=dist[i];
        }
    dist.clear();
    dist.resize(n+1,1);
    viz.clear();
    viz.resize(n+1,false);
    dfs(maxim.indice,dist,viz,la);
    for(int i=1; i<=n; ++i)
        if(maxim.distanta<dist[i])
        {
            maxim.indice=i;
            maxim.distanta=dist[i];
        }
    fout<<maxim.distanta<<'\n';
    return 0;
}