#include <bits/stdc++.h>

using namespace std;
ifstream in("darb.in");
ofstream out("darb.out");
int n, x, y, nmax;
vector<int> adj[100005];
int d[100005];

void bfs(int nod) {
    for (int i = 1; i <= n; i++)
        d[i] = 1e9;
    d[nod] = 1;
    queue<int> q;
    q.push(nod);

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

        for (auto it : adj[nod])
            if (d[it] > d[nod] + 1) {
                d[it] = d[nod] + 1;
                q.push(it);
            }
    }
}
int main()
{
    in >> n;
    for (int i = 1; i < n; i++) {
        in >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }

    bfs(1);
    nmax = -1;
    for (int i = 1; i <= n; i++)
        if (nmax == -1 || d[i] > d[nmax]) {
            nmax = i;
        }

    bfs(nmax);

    int dmax = 0;
    for (int i = 1; i <= n; i++)
        dmax = max(dmax, d[i]);

    out << dmax << '\n';
    return 0;
}