#include <fstream>
#include <vector>

#define NMAX 100010

using namespace std;


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

void BFS(int x);

struct elem
{
    int nod, dist;
}C[NMAX], el;

int n, m, i, j, x, y, k;
int sc, ic;
vector<int> M[NMAX];
bool v[NMAX];

int main()
{
    fin >> n;
    for(i = 1; i <= n; ++i)
    {
        fin >> x >> y;
        M[x].push_back(y);
        M[y].push_back(x);
    }
    BFS(1);
    for(i = 1; i <= n; ++i)
        v[i] = false;
    BFS(C[sc].nod);
    fout << C[sc].dist << '\n';
    return 0;
}

void BFS(int x)
{
    int i;
    ic = sc = 1;
    C[1].nod = x;
    C[1].dist = 1;
    v[x] = true;
    while(ic <= sc)
    {
        el = C[ic];
        ic++;
        for(i = 0; i < M[el.nod].size(); ++i)
            if(v[M[el.nod][i]] == false)
            {
                sc++;
                C[sc].nod = M[el.nod][i];
                C[sc].dist = el.dist+1;
                v[M[el.nod][i]] = true;
            }
    }
}