#include<cstdio>
#include<iostream>
#include<vector>
#include<cstring>
#include<algorithm>
using namespace std;
int n,k;
vector<int> road[200005];
int maxndis=-0x3fffffff;
int pointa,pointb,pointmid;
int vis[100005],ans[100005],tf;
int maxdep[100005],dep[100005];
int sum[100005];
int final_ans=-1;
bool cmp(int x,int y)
{
	return x>y;
}
void dfs(int cur,int step)
{
	if(vis[cur]==1){
		return;
	}
	vis[cur]=1;
	if(step>maxndis){
		maxndis=step;
		pointa=cur;
	}
	for(int i=0;i<(int)road[cur].size();i++){
		dfs(road[cur][i],step+1);
	}
}
void dfs1(int cur,int step)
{
	if(vis[cur]==1){
		return;
	}
	vis[cur]=1;
	if(step>maxndis){
		maxndis=step;
		pointb=cur;
	}
	for(int i=0;i<(int)road[cur].size();i++){
		dfs1(road[cur][i],step+1);
	}
}
void getmid(int cur,int step)
{
	if(vis[cur]==1){
		return;
	}
	if(tf==1){
		return;
	}
	vis[cur]=1;
	ans[step]=cur;
	if(cur==pointb){
		tf=1;
		return;
	}
	for(int i=0;i<(int)road[cur].size();i++){
		getmid(road[cur][i],step+1);
	}
}
void dfs2(int cur,int step)
{
	if(vis[cur]==1){
		return;
	}
	maxdep[cur]=dep[cur]=step;
	vis[cur]=1;
	for(int i=0;i<(int)road[cur].size();i++){
		dfs2(road[cur][i],step+1);
		maxdep[cur]=max(maxdep[cur],maxdep[road[cur][i]]);
	}
}
int main()
{
	cin>>n>>k;
	for(int i=1;i<=n-1;i++){
		int u,v;
		cin>>u>>v;
		road[u].push_back(v);
		road[v].push_back(u);
	}
	dfs(1,0);
	memset(vis,0,sizeof(vis));
	maxndis=-0x3fffffff;
	dfs1(pointa,1);
	memset(vis,0,sizeof(vis));
	getmid(pointa,1);
	pointmid=ans[(maxndis+1)/2];
	memset(vis,0,sizeof(vis));
	dfs2(pointmid,1);
	for(int i=1;i<=n;i++){
		sum[i]=maxdep[i]-dep[i];
	}
	sort(sum+1,sum+1+n,cmp);
	cout<<sum[k+1]+1;
	return 0;
}

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