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

vector<vector<int>> tree;
vector<int> dist;

void bfs(int start, int &farthest) {
    queue<int> q;
    q.push(start);
    dist[start] = 0;
    while (!q.empty()) {
        int node = q.front();
        q.pop();
        for (int neighbor : tree[node]) {
            if (dist[neighbor] == -1) {
                dist[neighbor] = dist[node] + 1;
                q.push(neighbor);
                if (dist[neighbor] > dist[farthest]) farthest = neighbor;
            }
        }
    }
}

int longestPath(int n) {
    dist.assign(n + 1, -1);
    int farthest = 1;
    bfs(1, farthest);
    dist.assign(n + 1, -1);
    bfs(farthest, farthest);
    return dist[farthest];
}

int main() {
    int n, u, v;
    cin >> n;
    tree.assign(n + 1, vector<int>());
    for (int i = 0; i < n - 1; i++) {
        cin >> u >> v;
        tree[u].push_back(v);
        tree[v].push_back(u);
    }
    cout << longestPath(n);
    return 0;
}