#include <iostream> 
#include <fstream>
 #include <vector>
 #include <queue>
 #include <string.h> 
  #define MAX_N 1000001
   using namespace std;
   ifstream f("darb.in");
 ofstream g("darb.out");
   vector<int> nod[MAX_N];
 queue<int> coada;
 int n,contor[MAX_N],viz[MAX_N],last,diametru;
   void bfs(int plecare)
{     memset(contor,0,MAX_N);     
memset(viz,0,MAX_N);     
coada.push(plecare);     
contor[plecare]=1;     
viz[plecare]=1;   
  int i,el;
     while(!coada.empty())
{         el=coada.front();
         for(i=0;i<nod[el].size();i++)
{             if(viz[nod[el][i]]==0)
{                 coada.push(nod[el][i]);
                 contor[nod[el][i]]=contor[el]+1;
                 viz[nod[el][i]]=1;
                   diametru=contor[nod[el][i]];
                 last=nod[el][i];
             }         }
         coada.pop();     } }
   void citire()
{     int i,a,b;
     f>>n;
     for(i=0;i<n-1;i++)
{         f>>a>>b;
         nod[a].push_back(b);
         nod[b].push_back(a);
     } } 
  int main()
 {     citire(); 
    bfs(1);  
    bfs(last);
     g<<diametru;
     return 0;
 }