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

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

#define NMAX 100005

vector<int> A[NMAX];
queue<int> Q;
int dist[NMAX];

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

    dist[start] = 1;
    Q.push(start);
    while (Q.size()) {
        int nod = Q.front();
        Q.pop();

        for (auto it : A[nod]) {
            if (dist[it] == -1) {
                dist[it] = dist[nod] + 1;
                Q.push(it);
            }
        }
    }

    int nod = 1;
    for (int i = 2; i <= n; ++i) {
        if (dist[i] > dist[nod]) {
            nod = i;
        }
    }
    return nod;
}

int main() {
    int n;
    fin >> n;
    for (int i = 1; i < n; ++i) {
        int a, b;
        fin >> a >> b;

        A[a].push_back(b);
        A[b].push_back(a);
    }

    int nod = bfs(1, n);
    nod = bfs(nod, n);

    fout << dist[nod];
    return 0;
}