#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
const ll ILL=2167167167167167167;
const int INF=2100000000;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=0){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
    if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
    else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}



void solve();
// CYAN / FREDERIC
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    int N, K;
    cin >> N >> K;
    vector<ll> X(N + 1), Y(N + 1);
    rep(i, 0, N) cin >> X[i] >> Y[i];
    vector dist(N + 1, vector<ld>(N + 1));
    rep(i, 0, N + 1) rep(j, 0, N + 1){
        dist[i][j] = sqrtl(powl(X[i] - X[j], 2) + powl(Y[i] - Y[j], 2));
    }
    vector dp(K, vector(N, vector<ld>(1 << N, ILL)));
    rep(i, 0, N) dp[K - 1][i][1 << i] = dist[i][N];
    rep(k, 0, 1 << N) rep(i, 0, K) rep(j, 0, N)  if (k & (1 << j)){
        rep(l, 0, N) if ((k & (1 << l)) == 0){
            if (i){
                chmin(dp[i - 1][l][k + (1 << l)], dp[i][j][k] + dist[j][l]);
            }
            chmin(dp[K - 1][l][k + (1 << l)], dp[i][j][k] + dist[j][N] + dist[l][N]);
        }
    }
    ld ans = ILL;
    rep(i, 0, K) rep(j, 0, N) chmin(ans, dist[j][N] + dp[i][j][(1 << N) - 1]);
    cout << fixed << setprecision(20) << ans << "\n";
}