#include <iostream>
#include <fstream>
#include <vector>
#include <list>
#include <queue>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
int n,m;
vector <list <int> >L;
void Citire()
{
    int x,y;
    fin>>n;
    L.resize(n+1);
    for(int i=1;i<=n-1;i++)
    {
        fin>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
}
vector<int> viz;
void DFS(int x)
{
    viz[x]=1;
    for(list<int>::iterator it=L[x].begin(); it!=L[x].end(); it++)
        if(viz[*it]==0) DFS(*it);
}
int CompConexe()
{
    viz.resize(n+1);
    int nr=0;
    for(int i=1;i<=n; i++)
        if(viz[i]==0)
        {
            nr++;
            DFS(i);
        }
    return nr;
}

vector<int> pred;
int BFS(int x)
{
    int ultim=0;
    queue <int> Q;
    vector<int> viz;
    viz.resize(n+1);
    for(int i=1;i<=n;i++) viz[i]=0;
    Q.push(x);
    pred[x]=0;
    viz[x]=1;
    while(!Q.empty())
    {
        int v=Q.front(); Q.pop();
        ultim=v; ///ultimul nod din BF este cel mai departat de x
        for(list <int> ::iterator it=L[v].begin(); it!=L[v].end(); it++)
            if(viz[*it]==0)
        {
            viz[*it]=1;
            pred[*it]=v;
            Q.push(*it);
        }
    }
    return ultim;
}
int main()
{
    Citire();
    //if(TestArbore()) fout<<"Este arbore.\n";
    //else fout<<"Nu este arbore.\n";
    pred.resize(n+1);
    int u=BFS(1); ///u va fi extremitatea unui lant elementar maxim
    int v=BFS(u); ///lantul uv determiat de BFS este maxim

    ///diametrul arborelui=lungimea lantului uv
    ///diametrul este cea mai mare distantă dintre două vârfuri
    int diametru=0;
    int x=v;
    while(x!=u)
    {
        diametru++;
        x=pred[x];
    }
   /* int raza=(diametru+1)/2;
    fout<<"Diametrul: "<<diametru<<"\n";
    fout<<"Raza: "<<raza<<"\n";
    fout<<"Centrul: ";
    ///urcam pana la mijlocul lantului
    x=v;
    for(int i=1; i<=raza-diametru%2; i++)
        x=pred[x];
    if(diametru%2==0) fout<<x;
    else fout<<x<<" "<<pred[x];*/
    fout<<diametru+1;
    return 0;
}