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

using namespace std;

const int Nmax = 100000;
vector <int> G[Nmax];
int diam;

void citire(int &n)
{
	ifstream f("darb.in");
	f >> n;
	int x, y;
	for (int i = 0; i < n; i++) {
		f >> x >> y;
		G[x].push_back(y);
		G[y].push_back(x);
	}
	f.close();
}

int bfs(int n, int s)
{
	int viz[Nmax + 1] = {0};
	queue <int> Q;
	int i, z;
	Q.push(s);
	viz[s] = 1;
	while (!Q.empty()) {
		s = Q.front();
		for (i = 0; i < G[s].size(); i++)
			if (!viz[G[s][i]]) {
				viz[G[s][i]] = viz[s] + 1;
				z = G[s][i];
				diam = viz[z];
				Q.push(G[s][i]);
			}
		Q.pop();
	} 
	return z;
}

int main()
{
	int n,a,z;
	citire(n);
	a = bfs(n, 1);
	z = bfs(n, a);
	ofstream g("darb.out");
	g << diam;
	g.close();
	return 0;
}