#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

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

const int nmax = 100001;
int N;
vector<int> g[nmax];
int dist[nmax];

int bfs(int start) {
    for (int i = 1; i <= N; i++) {
        dist[i] = -1;
    }

    queue<int> q;
    q.push(start);
    dist[start] = 0;

    int farthest = start;

    while (!q.empty()) {
        int node = q.front();
        q.pop();

        for (int i = 0; i < g[node].size(); i++) {
            int vecin = g[node][i];
            if (dist[vecin] == -1) {
                dist[vecin] = dist[node] + 1;
                q.push(vecin);

                if (dist[vecin] > dist[farthest]) {
                    farthest = vecin;
                }
            }
        }
    }

    return farthest;
}

int main() {
    fin >> N;

    for (int i = 1; i <= N - 1; i++) {
        int a, b;
        fin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }

    int A = bfs(1);
    int B = bfs(A);

    fout << dist[B] + 1;

    return 0;
}