#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
#endif
using ll=long long;
using ull=unsigned long long;
using P=pair<ll,ll>;
template<typename T>using minque=priority_queue<T,vector<T>,greater<T>>;
template<typename T>bool chmax(T &a,const T &b){return (a<b?(a=b,true):false);}
template<typename T>bool chmin(T &a,const T &b){return (a>b?(a=b,true):false);}
template<typename T1,typename T2>istream &operator>>(istream &is,pair<T1,T2>&p){is>>p.first>>p.second;return is;}
template<typename T>istream &operator>>(istream &is,vector<T> &a){for(auto &i:a)is>>i;return is;}
template<typename T1,typename T2>void operator++(pair<T1,T2>&a,int n){a.first++,a.second++;}
template<typename T1,typename T2>void operator--(pair<T1,T2>&a,int n){a.first--,a.second--;}
template<typename T>void operator++(vector<T>&a,int n){for(auto &i:a)i++;}
template<typename T>void operator--(vector<T>&a,int n){for(auto &i:a)i--;}
#define reps(i,a,n) for(int i=(a);i<int(n);i++)
#define rep(i,n) reps(i,0,n)
#define all(x) x.begin(),x.end()
#define pcnt(x) __builtin_popcountll(x)
#define fin(x) return cout<<(x)<<'\n',static_cast<void>(0)
ll myceil(ll a,ll b){return (a+b-1)/b;}
template<typename T,size_t n,size_t id=0>
auto vec(const int (&d)[n],const T &init=T()){
  if constexpr (id<n)return vector(d[id],vec<T,n,id+1>(d,init));
  else return init;
}
#ifdef LOCAL
#include<debug.h>
#else
#define debug(...) static_cast<void>(0)
#define debugg(...) static_cast<void>(0)
template<typename T1,typename T2>ostream &operator<<(ostream &os,const pair<T1,T2>&p){os<<p.first<<' '<<p.second;return os;}
#endif
void SOLVE();
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout<<fixed<<setprecision(16);
  #ifdef LOCAL
  clock_t start=clock();
  #endif
  int testcase=1;
  //cin>>testcase;
  for(int i=0;i<testcase;i++){
    SOLVE();
  }
  #ifdef LOCAL
  cerr<<"time:";
  cerr<<(clock()-start)/1000;
  cerr<<"ms\n";
  #endif
}
#include<type_traits>
template<typename T>constexpr std::enable_if_t<std::is_floating_point_v<T>,T> epsilon(){return 1e-10;}
template<typename T>constexpr std::enable_if_t<std::is_integral_v<T>,T>epsilon(){return 0;}
template<typename T>
struct Point{
  static_assert(std::is_arithmetic_v<T>);
  static constexpr T eps=epsilon<T>();
  T x,y;
  constexpr Point():x(0),y(0){}
  constexpr Point(T x_,T y_):x(x_),y(y_){}
  Point &operator+=(const Point&rhs){
    this->x+=rhs.x;
    this->y+=rhs.y;
    return *this;
  }
  Point &operator-=(const Point&rhs){
    this->x-=rhs.x;
    this->y-=rhs.y;
    return *this;
  }
  Point &operator*=(const T&rhs){
    this->x*=rhs;
    this->y*=rhs;
    return *this;
  }
  Point &operator/=(const T&rhs){
    this->x/=rhs;
    this->y/=rhs;
    return *this;
  }
  friend Point operator+(const Point&lhs,const Point&rhs){return Point(lhs)+=rhs;}
  friend Point operator-(const Point&lhs,const Point&rhs){return Point(lhs)-=rhs;}
  friend Point operator*(const Point&lhs,const T&rhs){return Point(lhs)*=rhs;}
  friend Point operator/(const Point&lhs,const T&rhs){return Point(lhs)/=rhs;}
  friend bool operator==(const Point&lhs,const Point&rhs){return std::abs(lhs.x-rhs.x)<=eps&&std::abs(lhs.y-rhs.y)<=eps;}
  friend bool operator!=(const Point&lhs,const Point&rhs){return !(lhs==rhs);}
  friend std::istream &operator>>(std::istream&is,Point&p){
    is>>p.x>>p.y;
    return is;
  }
  friend std::ostream &operator<<(std::ostream&os,const Point&p){
    os<<p.x<<' '<<p.y;
    return os;
  }
  T arg()const{
    static_assert(std::is_floating_point_v<T>);
    return atan2l(y,x);
  }
  Point<T>rot(T theta)const{
    static_assert(std::is_floating_point_v<T>);
    T s=sin(theta),c=cos(theta);
    return Point(c*x-s*y,s*x+c*y);
  }
  Point<T>rot90(){
    return Point(-y,x);
  }
  T norm()const{return x*x+y*y;}
};
template<typename T>
T cross(const Point<T>&a,const Point<T>&b){return a.x*b.y-a.y*b.x;}
template<typename T>
T dot(const Point<T>&a,const Point<T>&b){return a.x*b.x+a.y*b.y;}
void SOLVE(){
  int n,k;
  cin>>n>>k;
  vector<Point<double>>a(n);
  cin>>a;
  vector<vector<double>>dp(1<<n,vector<double>(n,1e18));
  rep(i,n)dp[1<<i][i]=sqrt(a[i].norm());
  rep(i,1<<n)rep(j,n)if(i>>j&1)rep(k,n)if(!(i>>k&1))chmin(dp[i|1<<k][k],dp[i][j]+sqrt((a[k]-a[j]).norm()));
  vector<double>opt(1<<n);
  rep(i,1<<n){
    opt[i]=1e18;
    if(pcnt(i)<=k){
      rep(j,n)chmin(opt[i],dp[i][j]+sqrt(a[j].norm()));
    }
  }
  vector<double>ep(1<<n,1e18);
  ep[0]=0;
  rep(i,1<<n){
    reps(j,i+1,1<<n){
      j|=i;
      chmin(ep[j],ep[i]+opt[i^j]);
    }
  }
  cout<<ep.back()<<endl;
}