#include <bits/stdc++.h>

using namespace std;

int n, sol[100001];
vector<int>a[100001];
queue<int>q;

inline void Citire()
{
    int i, x, y;
    ifstream fin("darb.in");
    fin >> n;
    for(i = 1; i <= n; ++i)
    {
        fin >> x >> y;
        if(x != y)
            a[x].push_back(y);
            a[y].push_back(x);
    }
    fin.close();
}

inline void BFS(int s)
{
    int i, j;
    unsigned int k;

    for(i = 1; i <= n; ++i)
        sol[i] = -1;
    sol[s] = 0;
    q.push(s);
    while(!q.empty())
    {
        i = q.front();
        q.pop();
        for(k = 0; k < a[i].size(); ++k)
        {
            j = a[i][k];
            if(sol[j] == -1)
            {
                sol[j] = 1 + sol[i];
                q.push(j);
            }
        }
    }
}

int main()
{
    int maxim, nod, i;
    Citire();
    BFS(1);
    maxim = 0;
    for(i = 1; i <= n; ++i)
        if(sol[i] > maxim)
        {
            maxim = sol[i];
            nod = i;
        }
    BFS(nod);
    for(i = 1; i <= n; ++i)
        maxim = max(maxim, sol[i]);
    maxim++;
    ofstream fout("darb.out");
    fout << maxim <<"\n";
    fout.close();

    return 0;
}