#include<bits/stdc++.h>
using namespace std;
const int MAXN=30;
int n,K;
long double x[MAXN],y[MAXN],dis[MAXN][MAXN];
int main(){
	cin >> n >> K;
	for (int i=0; i<n; i++) {
    cin >> x[i] >> y[i];
	}
	x[n]=0; y[n]=0;
	for (int i=0; i<=n;i++) {
    for (int j=0; j<=n; j++) {
      dis[i][j]=sqrtl((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]));
    }
	}
	vector<vector<vector<long double>>> dp(1<<n, vector<vector<long double>>(n+1, vector<long double>(K+1, 2e18)));
	dp[0][n][K]=0;
	for(int i=0; i<(1<<n); i++){
		for(int j=0; j<=n; j++){
			if(j<n && !((i >> j) & 1)) {}
			for(int k=1; k<=K; k++){
				for(int o=0; o<n; o++){
					if((i >> o) & 1) {
              continue;
					}
					dp[i|(1<<o)][o][k-1]=min(dp[i|(1<<o)][o][k-1],dp[i][j][k]+dis[j][o]);
				}
			}
			for(int k=0; k<=K; k++) {
                dp[i][n][K]=min(dp[i][n][K], dp[i][j][k]+dis[j][n]);
			}
		}
	}
	cout << fixed << setprecision(15) << dp[(1<<n)-1][n][K] << "\n";
	return 0;
}