#include <iostream>
#include <vector>
#include <queue>
#include <fstream>
using namespace std;

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

#define Nmax 100002
#define INF 100002

vector<int> graph[Nmax];

int d[Nmax];
queue <int> q;

int n; // numarul de noduri al arborelui

void bfs(int s) {
    int i, x, y;

    // initializare vector d
    for (i = 1; i <= n; i++) {
        d[i] = INF;
    }

    // inserez nodul sursa in coada
    q.push(s);
    d[s] = 0;

    while (!q.empty()) {
        x = q.front(); // extrag nodul de la inceputul cozii
        q.pop(); // eliminare nod de la inceputul cozii

        // parcurg vecinii nodului x
        for (i = 0; i < graph[x].size(); i++) {
            y = graph[x][i];
            if (d[y] > d[x] + 1) {
                // actualizare distanta
                d[y] = d[x] + 1;
                // inserare in coada vecin y
                q.push(y);
            }
        }
    }
}

int main()
{
    int i, x, y;

    in >> n;

    for (i = 0; i < n - 1; i++) {
        in >> x >> y;
        // graf neorientat
        graph[x].push_back(y);
        graph[y].push_back(x);
    }

    bfs(1);

    // for (i = 1; i <= n; i++) {
    //     cout << d[i] << " ";
    // }
    // cout << '\n';

    int dist_max = d[1];
    int pos_dist_max = 1;

    for (i = 2; i <= n; i++) {
        if (d[i] > dist_max) {
            dist_max = d[i];
            pos_dist_max = i;
        }
    }

    // cout << dist_max << '\n';
    // cout << pos_dist_max << '\n';

    bfs(pos_dist_max);

    // for (i = 1; i <= n; i++) {
    //     cout << d[i] << " ";
    // }
    // cout << '\n';

    int diametru = d[1];
    for (i = 1; i <= n; i++) {
        if (d[i] > diametru) {
            diametru = d[i];
        }
    }

    out << diametru + 1 << '\n';

    return 0;
}