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

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#define int long long

using ld=long double;

signed main(){
	int N,K;cin>>N>>K;
	vector<int> X(N+1),Y(N+1);
	for(int i=0;i<N;i++){
		cin>>X[i]>>Y[i];
	}
	
	X[N]=0,Y[N]=0;

	vector<vector<ld>> d(N+1,vector<ld>(N+1));

	for(int i=0;i<=N;i++){
		for(int j=0;j<=N;j++){
			d[i][j]=hypotl(X[i]-X[j],Y[i]-Y[j]);
		}
	}

	// cout<<"!"<<endl;

	vector<vector<ld>> dpdp(1<<(N+1),vector<ld>(N+1,1e18));

	dpdp[0][N]=0;

	for(int S=0;S<(1<<(N+1));S++){
		for(int i=0;i<=N;i++){
			for(int j=0;j<=N;j++){
				if(S>>j&1)continue;
				dpdp[S|(1<<j)][j]=min(dpdp[S|(1<<j)][j],dpdp[S][i]+d[i][j]);
			}
		}
	}

	// for(int S=0;S<(1<<(N+1));S++){
	// 	cout<<dpdp[S][N]<<" ";
	// }
	// cout<<endl;

	
	// cout<<"!"<<endl;

	vector<ld> dp(1<<N,1e18);

	dp[0]=0;

	for(int S=0;S<(1<<N);S++){
		int al=(1<<N)-1;

		int st=al^S;
		int sub=st;

		while(sub){
			if(__popcount(sub)<=K){
				dp[S|sub]=min(dp[S|sub],dp[S]+dpdp[sub|(1<<N)][N]);
			}
			sub=(sub-1)&st;
		}
	}

	cout<<fixed<<setprecision(20)<<dp[(1<<N)-1]<<endl;
}