#include "bits/stdc++.h"

using namespace std;

#define int long long
#define ll long long
typedef pair<int, int> P;
#define mod 1000000007
#define INF (1LL<<60)

#define rep(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define YES cout << "YES" << endl;
#define Yes cout << "Yes" << endl;
#define NO cout << "NO" << endl;
#define No cout << "No" << endl;

int dist[123456];
vector<vector<int>> g;

void bfs(int s){
	queue<int> q;
	q.push(s);
	dist[s] = 0;
	while(!q.empty()){
		int u = q.front(); q.pop();
		for (int v : g[u]){
			if (dist[v] == INF)	{
				dist[v] = min(dist[v], dist[u] + 1);
				q.push(v);
			}
		}
	}
}

signed main(){

	int N;
	cin >> N;
	g.assign(N, vector<int>());
	rep(i, N - 1){
		int a, b;
		cin >> a >> b;
		a--; b--;
		g[a].push_back(b);
		g[b].push_back(a);
	}

	rep(i, 123456) dist[i] = INF;
	
	bfs(0);
	int ma = -INF, maidx;
	rep(i, N){
		if (dist[i] > ma){
			ma = dist[i];
			maidx = i;
		}
	}

	rep(i, 123456) dist[i] = INF;
	bfs(ma);

	ma = -INF;
	rep(i, N){
		if (dist[i] > ma){
			ma = dist[i];
			maidx = i;
		}
	}

	cout << N-1-ma << endl;
	return 0;
}