#include <iostream>
#include <fstream>
#include <vector>
#define N 100001
#define INF 2000000
#include <deque>

using namespace std;

vector <int> graph[N];
deque <int> q;
int dist[N],last;

void bf(int nod)
{
    int ve;
    dist[nod]=1;
    q.push_back(nod);
    while(!q.empty())
    {
        nod=q.front();
        q.pop_front();
        for(int i=0;i<graph[nod].size();++i)
        {
            ve=graph[nod][i];
            if(dist[ve]>dist[nod]+1)
            {
                dist[ve]=dist[nod]+1;
                last=ve;
                q.push_back(ve);
            }
        }
    }
}
int main()
{
    ifstream f("darb.in");
    ofstream g("darb.out");
    int n,x,y;
    f>>n;
    for(int i=1;i<=n;++i)
    {
        f>>x>>y;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    for(int i=1;i<=n;++i) dist[i]=INF;
    bf(1);
    for(int i=1;i<=n;++i) dist[i]=INF;
    bf(last);
    g<<dist[last];
    return 0;
}