#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");

vector<int> ADJ[100005];

int N,rez,NOD;

bool VIZ[100005];

void df (int nod,int dist)
{
    if (dist>rez)
    {
        rez=dist;
        NOD=nod;
    }
    VIZ[nod]=1;
    vector<int> :: iterator it;
    for (it=ADJ[nod].begin();it!=ADJ[nod].end();++it)
    {
        int vecin=(*it);
        if (VIZ[vecin]==0)
        {
            df(vecin,dist+1);
        }
    }
}

int main()
{
    fin >> N;
    int i;
    for (i=1;i<=N;++i)
    {
        int a,b;
        fin >> a >> b;
        ADJ[a].push_back(b);
        ADJ[b].push_back(a);
    }
    df(1,1);
    for (i=1;i<=N;++i)
    {
        VIZ[i]=0;
    }
    df(NOD,1);
    fout << rez;
    fin.close();
    fout.close();
    return 0;
}