#include <bits/stdc++.h>
#define nmax 100005

using namespace std;

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

int n,d[nmax],nodmax;
vector <int> L[nmax];
bitset <nmax> viz;

void Citire()
{
    int x,y;
    fin >> n;
    while(fin >> x >> y)
    {
        L[x].push_back(y);
        L[y].push_back(x);
    }
}

void BFS(int k)
{
    int nod;
    fill(d+1,d+n+1,0);
    viz.reset();
    viz[k] = 1;
    d[k] = 1;
    queue <int> q;
    q.push(k);
    while(!q.empty())
    {
        nod = q.front();
        q.pop();
        for(auto i : L[nod])
            if(viz[i] == 0)
            {
                viz[i] = 1;
                d[i] = max(d[i],d[nod]+1);
                if(d[i] > d[nodmax])
                    nodmax = i;
                q.push(i);
            }
    }
}

int main()
{
    Citire();
    BFS(1);
    BFS(nodmax);
    fout << d[nodmax] << "\n";

    fin.close();
    fout.close();
    return 0;
}