#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#define maxv 100500

#define maxe 200500

#define inf 2000000000

using namespace std;

int n,k,x,y,g[maxv],nume=,fath_w[maxv],dis[maxv],pos,ret=,root=,tot=,fath[maxv];

int dp1[maxv],dp2[maxv],ans=-inf;

struct edge

{

     int v,w,nxt;

}e[maxe];

void addedge(int u,int v,int w)

{

    e[++nume].v=v;

    e[nume].w=w;

    e[nume].nxt=g[u];

    g[u]=nume;

}

void dfs1(int x)

{

    for (int i=g[x];i;i=e[i].nxt)

    {

        int v=e[i].v;

        if (v!=fath[x])

        {

            dis[v]=dis[x]+e[i].w;

            fath_w[v]=i;fath[v]=x;

            if (dis[v]>ret)

            {

                ret=dis[v];

                pos=v;

            }

            dfs1(v);

        }

    }

}

int get_d()

{

     dis[root]=;ret=-inf;memset(fath,,sizeof(fath));dfs1(root);

     root=pos;

     dis[root]=;ret=-inf;memset(fath,,sizeof(fath));dfs1(root);

     return ret;

}

void get_labled(int x)

{

    while (x!=root)

    {

        e[fath_w[x]].w=e[fath_w[x]^].w=-;

        x=fath[x];

    }

}

void dfs2(int x)

{

    dp1[x]=dp2[x]=;

    for (int i=g[x];i;i=e[i].nxt)

    {

        int v=e[i].v;

        if (v!=fath[x])

        {

            dfs2(v);

            if (dp1[v]+e[i].w>dp1[x]) {dp2[x]=dp1[x];dp1[x]=dp1[v]+e[i].w;}

            else if (dp1[v]+e[i].w>dp2[x]) dp2[x]=dp1[v]+e[i].w;

        }

    }

    ans=max(ans,dp1[x]+dp2[x]);

}

int main()

{

    scanf("%d%d",&n,&k);

    for (int i=;i<=n-;i++)

    {

        scanf("%d%d",&x,&y);

        addedge(x,y,);addedge(y,x,);

    }

    tot+=get_d();

    if (k==) {printf("%d\n",*n--tot);return ;}

    get_labled(pos);

    dfs2(root);tot+=ans;

    printf("%d\n",*n-tot);

    return ;

}