#include <bits/stdc++.h>

using namespace std;

vector <int> h[100001];
int n, d[100001], viz[100001];

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

int BFS(int k)
{
    queue<int> q;
    int i, j;
    d[k] = 1;
    viz[k] = 1;
    q.push(k);
    while (!q.empty())
    {
        k = q.front();
        q.pop();
        for (j = 0; j < h[k].size(); j++)
        {
            i = h[k][j];
            if (!viz[i])
            {
                viz[i] = 1;
                d[i] = d[k] + 1;
                q.push(i);
            }
        }
    }
    j = 1;
    for (i = 2; i <= n; ++i)
        if (d[i] > d[j]) j = i;
    return j;
}

void Afisare()
{
    int i, j;
    i = BFS(1);
    for (j = 1; j <= n; j++)
        {viz[j] = 0;d[j] = 0;}
    j = BFS(i);
    ofstream fout("darb.out");
    fout << d[j] << "\n";
    fout.close();
}

int main()
{
    Citire();
    Afisare();
    return 0;
}