#include <bits/stdc++.h>

using namespace std;

const int NMAX = 100005;
int dist[NMAX], last;
vector<int> vec[NMAX];

void bfs (int start) {
    fill(dist, dist + NMAX - 1, 0);
    queue<int> q;
    dist[start] = 1;
    q.push(start);
    while (!q.empty()) {
        int fr = q.front();
        q.pop();
        for (auto y : vec[fr]) {
            if (!dist[y]) {
                dist[y] = dist[fr] + 1;
                last = y;
                q.push(y);
            }
        }
    }
}

int main () {
    freopen("darb.in", "r", stdin);
    freopen("darb.out", "w", stdout);
    int N;
    cin >> N;
    for (int i = 0; i < N - 1; ++i) {
        int a, b;
        cin >> a >> b;
        vec[a].push_back(b);
        vec[b].push_back(a);
    }
    bfs(1);
    bfs(last);
    cout << dist[last];
    return 0;
}