#include <fstream>
#include <vector>
#include <bitset>
using namespace std;

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

int N;
vector<int> g[100002], d;
bitset<100003> v;

void citire()
{
    d.resize(100002);

    int i, j;
    fin >> N;
    while (fin >> i >> j)
    {
        g[i].push_back(j);
        g[j].push_back(i);
    }
}

void dfs(int nod, int dist)
{
    v[nod] = 1;
    d[nod] = dist;
    for (auto i : g[nod])
    {
        if (!v[i])
            dfs(i, dist + 1);
    }
}

int main()
{
    citire();
    dfs(1, 0);
    int dmax = 0, k;
    for (int i = 1; i <= N; i++)
    {
        if (d[i] > dmax)
        {
            dmax = d[i];
            k = i;
        }
    }

    v.reset();
    dfs(k, 0);
    dmax = 0;
    for (int i = 1; i <= N; i++)
    {
        if (d[i] > dmax)
        {
            dmax = d[i];
        }
    }
    fout << dmax;

    return 0;
}