#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define NMAX 100001
using namespace std;

vector<int> a[NMAX];

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

int n,x,y,d[NMAX],viz[NMAX];
queue<int> coada;

int bfs(int nod)
{
    coada.push(nod);
    d[nod] = 1; viz[nod] = 1;
    while(!coada.empty())
    {
        nod = coada.front();coada.pop();
        for(int i=0;i<a[nod].size();i++)
        {
            if(!viz[a[nod][i]])
            {
                d[a[nod][i]] = d[nod]+1;
                coada.push(a[nod][i]);
                viz[a[nod][i]]=1;

            }
        }

    }
    return nod;
}

int main()
{
    in >> n;
    for(int i=1;i<n;i++)
    {
        in >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }

    int nd = bfs(1);
    for(int i=1;i<=n;i++)
    {
        d[i] = 0;
        viz[i] = 0;
    }
    bfs(nd);
    int diam = 0;
    for(int i=1;i<=n;i++)
    {
      //  cout << d[i] << " ";
        diam = max(diam,d[i]);
    }
    out << diam;
    return 0;
}