#include <bits/stdc++.h>
#define nmax 100007

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

int n, viz[nmax], d[nmax];
vector <int> L[nmax];
queue <int> q;

void Citire()
{
    int x, y;
    fin >> n;
    for (int i = 1; i <= n; i++)
    {
        fin >> x >> y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
}

int BFS(int nod)
{
    int k;
    d[nod] = 1;
    viz[nod] = 1;
    q.push(nod);
    while (!q.empty())
    {
        k = q.front();
        q.pop();
        for (auto i : L[k])
            if (!viz[i])
            {
                viz[i] = 1;
                q.push(i);
                d[i] = d[k] + 1;
            }
    }
    k = 1;
    for (int i = 2; i <= n; i++)
        if (d[i] > d[k])
            k = i;
    return k;
}

int main()
{
    int i, j;
    Citire();
    i = BFS(1);
    for (j = 1; j <= n; j++)
    {
        viz[j] = 0;
        d[j] = 0;
    }
    j = BFS(i);
    /**
    for (i = 1; i <= n; i++)
        cout << d[i] << " ";
    //*/
    fout << d[j] << "\n";
    fin.close();
    fout.close();
    return 0;
}