#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream fin ("darb.in");
ofstream fout("darb.out");
int n, i, x, y, st, viz[2][100001];
vector <vector <int> > v;
void bfs (int c, int s)
{
    viz[c][s] = 1;
    queue <int> q;
    q.push(s);
    while (!q.empty())
    {
        s = q.front();
        q.pop();
        for (i = 0; i < v[s].size(); i++)
            if (viz[c][v[s][i]] == 0)
                viz[c][v[s][i]] = viz[c][s]+1, q.push(v[s][i]);
        if (viz[c][s] > viz[c][st])
            st = s;
    }
}
int main()
{
    fin >> n; v.resize(n+1);
    for (i = 1; i < n; i++)
    {
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    bfs(0, 1);
    bfs(1, st);
    fout << viz[1][st];
    return 0;
}