#include <fstream>
#include <queue>
#include <cstring>
#include <vector>

#define MAXN 100005
#define inf 0x3f3f3f3f

using namespace std;

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

int viz[MAXN];
queue <int> Q;
vector <int> graph[MAXN];

inline void BFS(int start) {
    int z;

    Q.push(start); viz[start] = 1;

    while (!Q.empty()) {
        z = Q.front();

        for (auto x : graph[z]) {
            if (viz[x] == 0) {
                viz[x] = viz[z] + 1;
                Q.push(x);
            }
        }

        Q.pop();
    }
}

inline void Read() {
    int N, x, y, p;

    fin >> N;

    for (int i = 1; i < N; i++) {
        fin >> x >> y;

        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    BFS(1);
    p = 0; viz[p] = 0;
    for (int i = 1; i <= N; i++) {
        if (viz[i] > viz[p])
            p = i;
    }
    memset(viz, 0, sizeof(viz));
    BFS(p);
    viz[0] = 0; p = 0;
    for (int i = 1; i <= N; i++) {
        if (viz[i] > viz[p])
            p = i;
    }

    fout << viz[p];
}

int main () {
    Read();

    fin.close(); fout.close(); return 0;
}