#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define cpy(a,b) copy(begin(a),end(a),begin(b))
#define ld long double
#define dot(x) fixed<<setprecision(x)
#define foru(a,b,c) for(ll a=b;a<=c;a++)

ll n,k,tot,dep[100005],fa[100005],l=1;
ll ans1,ans2,val[100005],t[100005];
vector<vector<pair<ll,ll>>>a(100005);

void dfs1(ll u,ll f,ll x){
    dep[u]=dep[f]+x;
    for(auto v:a[u]){
        ll y=v.first,x=v.second;
        if(y==f)continue;
        dfs1(y,u,x);
    }
    if(dep[u]>dep[l])l=u;
}

void dfs2(ll u,ll f,ll x){
    dep[u]=dep[f]+x;
    fa[u]=f;
    for(auto v:a[u]){
        ll y=v.first,x=v.second;
        if(y==f)continue;
        dfs2(y,u,x);
    }
    if(dep[u]>dep[l])l=u;
}

void calc(ll u,ll f){
    for(auto &v:a[u]){
        ll y=v.first;
        if(y==f)continue;
        if(val[u]&&val[y])v.second=-1;
        calc(y,u);
        ans2=max(ans2,t[u]+t[y]+v.second);
        t[u]=max(t[u],t[y]+v.second);
    }
}

int main(){
    freopen("xunluo.in" ,"r",stdin );
    freopen("xunluo.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    cin>>n>>k;
    foru(i,1,n-1){
        ll x,y;
        cin>>x>>y;
        a[x].push_back({y,1});
        a[y].push_back({x,1});
    }
    dfs1(1,0,0);
    dfs2(l,0,0);
    ans1=dep[l];
    if(k==1){
        cout<<2*(n-1)-ans1+1;
        return 0;
    }
    for(ll i=l;i;i=fa[i]){
        val[i]=1;
    }
    calc(1,0);
    cout<<n*2-ans1-ans2;
    return 0;
}