#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) (void(0))
#endif
void run_case();
int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int T = 1;
	// cin >> T;
	while (T--) run_case();
	return 0;
}
vector<int> G[2 << 17];
pair<int, int> dfs(int v, int p = - 1) {
	pair<int, int> ret{0, v};
	for(const auto&to: G[v]) if(to != p) {
		auto ch = dfs(to, v);
		ch.first += 1;
		ret = max(ret, ch);
	}
	return ret;
}
void run_case() {
	int N;
	cin >> N;
	for(int i = 0; i < N - 1; i++) {
		int a, b;
		cin >> a >> b;
		a--, b--;
		G[a].push_back(b);
		G[b].push_back(a);
	}
	auto D = dfs(0);
	D = dfs(D.second);
	int ans = 2 * (N - 1);
	ans -= D.first;
	cout << ans << endl;
}