#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
int d[100001];
using namespace std;
vector<int> Nout[100001];
int bfs(int n){
	memset(d, -1, sizeof(d));
	queue<int> q;
	q.push(n);
	d[n] = 0;
	int c=n;
	while (!q.empty()){
		int x = q.front();
		q.pop();
		for (auto& i : Nout[x])
			if (d[i] < 0){
				q.push(i);
				d[i] = d[x] + 1;
				c = i;
			}
	}
	return c;
}
int main(){
	fstream f("darb.in");
	ofstream of("darb.out");
	int N, a, b;
	f >> N;
	while (f >> a >> b){
		Nout[a].push_back(b);
		Nout[b].push_back(a);
	}
	of << d[bfs(bfs(1))]+1;
	return 0;
}