#include<iostream>
#include<cstring>
using namespace std;

const int MAXN = 1e5 + 5;

struct node{
	int to, nxt, len;
}e[MAXN * 2];

int tot = 0, h[MAXN];
int d[MAXN];
bool vis[MAXN];

void add(int x, int y, int len){
	e[++ tot] = {y, h[x], len};
	h[x] = tot;
}

int n, k, d1 = 1, d2 = 0, d3 = 1, d4 = 0;
int f[MAXN];
int dp[MAXN], maxx;

void dfs(int u, int fa){
    dp[u] = 0;
    for(int i = h[u]; i; i = e[i].nxt){
        int v = e[i].to;
        if(v == fa) continue;
        e[i].len = (vis[u] && vis[v]) ? -1 : 1;
        dfs(v, u);
        maxx = max(maxx, dp[u] + dp[v] + e[i].len);
		dp[u] = max(dp[u], dp[v] + e[i].len);
    }
}

void dfs1(int u, int fa){
	for(int i = h[u];i;i = e[i].nxt){
		int v = e[i].to;
		if(v == fa) continue;
		d[v] = d[u] + e[i].len;
		if(d[v] > d[d1]){
			d1 = v;
		}
		dfs1(v, u);
	}
}

void dfs2(int u, int fa){
	f[u] = fa;
	for(int i = h[u];i;i = e[i].nxt){
		int v = e[i].to;
		if(v == fa) continue;
		d[v] = d[u] + e[i].len;
		if(d[v] > d[d2]){
			d2 = v;
		}
		dfs2(v, u);
	}
}

int main(){
	freopen("xunluo.in", "r", stdin);
	freopen("xunluo.out", "w", stdout);
	ios::sync_with_stdio(0);
    cin.tie(0);
	
	cin >> n >> k;
	for(int i = 1;i < n;i ++){
		int a, b; cin >> a >> b;
		add(a, b, 1), add(b, a, 1);
	}

	dfs1(1, 0);
	memset(d, 0, sizeof(d));
	dfs2(d1, 0);
	int l1 = d[d2];

	if(k == 1){
		cout << 2 * (n - 1) - l1 + 1 << '\n';
		return 0;
	}

	memset(vis, 0, sizeof(vis));
	int tmp = d2;
	while(tmp != 0){
		vis[tmp] = true;
		tmp = f[tmp];
	}
	maxx = 0;
	dfs(1, 0);
	int l2 = maxx;

	cout << 2 * (n - 1) - (l1 - 1) - (l2 - 1) << '\n';

	return 0;
}