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#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;
}