#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define Nmax 100005
using namespace std;
ifstream fin("darb.in");
ofstream fout("darb.out");
int N,use[Nmax],dist[Nmax],last,m;
vector <int> G[Nmax];
queue <int> Q;
void read()
{
    fin>>N;
    for(int i=1;i<N;i++)
    {
        int x,y;
        fin>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
void solve()
{
    Q.push(1);
    use[1]++;
    while(!Q.empty())
    {
        int nod=Q.front();
        Q.pop();
        last=nod;
        for(int i=0;i<G[nod].size();++i)
        {
            int Vecin=G[nod][i];
            if(!use[Vecin])
            {
                use[Vecin]++;
                Q.push(Vecin);
            }
        }
    }

    Q.push(last);
    use[last]++;
    dist[last]=1;
    while(!Q.empty())
    {
        int nod=Q.front();
        Q.pop();
        for(int i=0;i<G[nod].size();++i)
        {
            int Vecin=G[nod][i];
            if(use[Vecin]<2)
            {
                use[Vecin]++;
                Q.push(Vecin);
                dist[Vecin]=dist[nod]+1;
                m=max(m,dist[Vecin]);
            }
        }
    }
    fout<<m<<"\n";
}
int main()
{
    read();
    solve();
    return 0;
}