#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <iterator>
#define Nmax 100000

using namespace std;

ifstream f("darb.in");
ofstream g("darb.out");

vector <int> adj[Nmax];
int visited[Nmax],contor[Nmax],diam,last,n;
queue <int> q;

void bfs(int x)
{
    int v,next;
    q.push(x);
    while(!q.empty())
    {
        v=q.front();
        q.pop();
        for(vector<int>::iterator it=adj[v].begin();it!=adj[v].end();it++ )
        {
            next=*it;
            if(!visited[next])
            {
                visited[next]=1;
                contor[next]=contor[v]+1;

                last=next;
                diam=contor[next];

                q.push(next);
            }
        }
    }
}

int main()
{

    f>>n;
    int x,y;
    for(int i=0;i<n;i++)
    {
        f >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }

    bfs(1);

    for(int i=1;i<=n;i++)
    {
        contor[i]=1;
        visited[i]=0;
    }

    bfs(last);

    g << diam << "\n";

    return 0;
}