#include<iostream>
#include<string>
#include<queue>
#include<vector>
#include<cassert>
#include<random>
#include<set>
#include<map>
#include<cassert>
#include<unordered_map>
#include<bitset>
#include<numeric>
#include<algorithm>
using namespace std;
using ll = long long;
const int inf=1<<30;
const ll INF=1LL<<62;
typedef pair<ll,ll> P;
typedef pair<int,P> PP; 
const ll MOD=998244353;
const int dy[]={0,1,0,-1};
const int dx[]={1,0,-1,0};
void chmin(double &a,const double &b){
    a=min(a,b);
}



int main(){
    int N,K;
    cin>>N>>K;
    vector<P> pos(N+1);
    for(int i=0;i<N;i++){
        cin>>pos[i].first>>pos[i].second;
    } 
    
    auto dist=[&](const P lhs,const P rhs)->double{
        double dx=lhs.first-rhs.first;
        double dy=lhs.second-rhs.second;
        return sqrt(dx*dx+dy*dy);
    };

    vector dp(1<<N,vector<vector<double>>(N,vector<double>(K+1,INF)));

    for(int i=0;i<N;i++){
        dp[1<<i][i][K-1]=dist({0,0},pos[i]);
    }

    for(int S=0;S<(1<<N);S++){
        for(int k=0;k<=K;k++){
            for(int now=0;now<N;now++){
                if(!(S>>now&1)) continue;

                for(int to=0;to<N;to++){
                    if((S>>to)&1) continue;

                    if(k-1>=0){
                        chmin(dp[S|1<<to][to][k-1],dp[S][now][k]+dist(pos[now],pos[to]));
                    }
                    chmin(dp[S|1<<to][to][K-1],dp[S][now][k]+dist(pos[now],{0,0})+dist({0,0},pos[to]));
                }
            }
        }
    }

    double ans=INF;
    for(int t=0;t<=K;t++){
        for(int i=0;i<N;i++){
            //街iで終わる
            chmin(ans,dp[(1<<N)-1][i][t]+dist(pos[i],{0,0}));
        }
    }
    printf("%.10f\n",ans);

}