#include <iostream>
#include <queue>
#include <vector>
#include <fstream>
using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
const int NMAX=100001;
vector<int> graf[NMAX];
int d[NMAX];
queue<int> q;
int n;
void bfs(int s)
{
    int x,y;
     for(int i=1; i<=n; i++)
        d[i]=-1;
    //punem 0 la sursa
    d[s]=0;
    q.push(s);
    while(q.empty()==false)
    {
        x=q.front();
        q.pop();
        //parcurg vecinii nodului x
        for(int j=0; j<graf[x].size(); j++)
        {
            y=graf[x][j];
            if(d[y]==-1 || d[y]>d[x]+1)
            {
                d[y]=d[x]+1;
                q.push(y);
            }

        }
    }
}
int main()
{
    int x,y;
   in>>n;
    for(int i=1; i<=n-1; i++)
    {
        in>>x>>y;
        //adaugam nodul y in lista de vecini ai nodului x
        graf[x].push_back(y);
        graf[y].push_back(x);

    }
    bfs(1);
    int d_maxim=d[1];
    int nod_dmax=1;
    for(int i=2; i<=n; i++)
        {
            if(d_maxim< d[i])
            {
                d_maxim=d[i];
                nod_dmax=i;
            }
        }
    bfs(nod_dmax);
    int diametru=d[1];
    for(int i=1; i<=n; i++)
        if(diametru<d[i])
            diametru=d[i];
    out<<diametru+1;



    return 0;
}