#include <iostream>
#include <fstream>
#include <vector>
#include <queue>


typedef std::vector<int>::iterator iter;


std::ifstream f("darb.in");
std::ofstream g("darb.out");
const int MAXN = 100005;
const int INF = 0x3f3f3f3f;
std::vector<int> G[MAXN]; int n;
int dist[MAXN];
std::queue<int> q;

void bfs(int nod)
{
	memset(dist, 0x3f, sizeof(dist));
	q.push(nod);
	dist[nod] = 0;

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

		for (iter it = G[nd].begin(); it != G[nd].end(); it++) {
			if (dist[*it] > dist[nd] + 1) {
				dist[*it] = dist[nd] + 1;
				q.push(*it);
			}
		}
	}
}


int main()
{
	f >> n;
	for (int i = 1, x, y; i <= n; i++) {
		f >> x >> y;

		G[x].push_back(y);
		G[y].push_back(x);
	}

	
	bfs(1);
	int nd = 1, mx = 0;
	for (int i = 1; i <= n; i++) {
		if (dist[i] >= mx) { mx = dist[i]; nd = i; }
	}
	bfs(nd);
	mx = 0;
	for (int i = 1; i <= n; i++) {
		mx = std::max(mx, dist[i]);
	}
	g << mx + 1 << std::endl;


	f.close();
	g.close();
	return 0;
}