#include<bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 2000010;
int n, k, ans, maxn, rt, vis[MAXN], cs[MAXN], cnt, flg, maxn2, rt2;
vector<int>cd[MAXN];
void dfs(int x, int fa, int s) {
	if(flg == 1 && s == maxn) {
		for(int i = 1; i <= cnt; i ++) {
			vis[cs[i]] = 1;
		}
		flg = 0;
	}
	if(s > maxn) {
		maxn = s;
		rt = x;
	}
	for(int i = 0; i < cd[x].size(); i ++) {
		int u = cd[x][i];
		if(u == fa) {
			continue;
		}
		cs[++ cnt] = u;
		dfs(u, x, s + 1);
		cnt --;
	}
}
void dfs2(int x, int fa, int s) {
	if(s > maxn2) {
		maxn2 = s;
		rt2 = x;
	}
	for(int i = 0; i < cd[x].size(); i ++) {
		int u = cd[x][i];
		if(u == fa || (vis[u] && vis[x])) {
			continue;
		}
		dfs2(u, x, s + 1);
		cnt --;
	}
}
signed main() {
    freopen("xunluo.in", "r", stdin);
    freopen("xunluo.out", "w", stdout);
	cin >> n >> k;
	for(int i = 1; i < n; i ++) {
		int x, y;
		cin >> x >> y;
		cd[x].push_back(y);
		cd[y].push_back(x);
	}
	dfs(1, 0, 0);
	dfs(rt, 0, 0);
	if(k == 1) {
		cout << n * 2 - maxn - 1;
		return 0;
	}
	ans = n * 2 - maxn - 1;
	flg = 1;
	vis[rt] = 1;
	dfs(rt, 0, 0);
	for(int i = 1; i <= n; i ++) {
		if(!vis[i]) {
			dfs2(i, 0, 0);
		}
	}
	dfs2(rt2, 0, 0);
	cout << ans - maxn2 + 1;
	return 0;
}