import java.io.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
    static double[] dp;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int k = sc.nextInt();
        Point[] points = new Point[n];
        for (int i = 0; i < n; i++) {
            points[i] = new Point(sc.nextInt(), sc.nextInt());
        }
        double[][] matrix = new double[n][n];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                matrix[i][j] = points[i].getDistance(points[j]);
            }
        }
        dp = new double[1 << n];
        Arrays.fill(dp, Double.MAX_VALUE);
        dp[0] = 0;
        double[][] routes = new double[n][1 << n];
        for (int i = 1; i < (1 << n); i++) {
            int count = Integer.bitCount(i);
            if (count > k) {
                continue;
            }
            for (int j = 0; j < n; j++) {
                if ((i & (1 << j)) == 0) {
                    continue;
                }
                if (count == 1) {
                    routes[j][i] = points[j].getFromBase();
                } else {
                    routes[j][i] = Double.MAX_VALUE;
                    for (int a = 0; a < n; a++) {
                        if (a == j || (i & (1 << a)) == 0) {
                            continue;
                        }
                        routes[j][i] = Math.min(routes[j][i], routes[a][i ^ (1 << j)] + matrix[a][j]);
                    }
                }
                dp[i] = Math.min(dp[i], routes[j][i] + points[j].getFromBase());
            }
        }
        System.out.println(new java.math.BigDecimal(dfw((1 << n) - 1)).toPlainString());
    }
    
    static double dfw(int mask) {
        if (dp[mask] == Double.MAX_VALUE) {
            for (int x = ((mask - 1) & mask); x > 0; x = ((x - 1) & mask)) {
                dp[mask] = Math.min(dp[mask], dfw(x) + dfw(mask ^ x));
            }
        }
        return dp[mask];
    }
    
    static class Point {
        double x;
        double y;
        
        public Point(double x, double y) {
            this.x = x;
            this.y = y;
        }
        
        public double getDistance(Point p) {
            return Math.sqrt(Math.pow(x - p.x, 2) + Math.pow(y - p.y, 2));
        }
        
        public double getFromBase() {
            return Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
        }
    }
}

class Scanner {
    BufferedReader br;
    StringTokenizer st = new StringTokenizer("");

    public Scanner() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            
        }
    }
    
    public int nextInt() {
        return Integer.parseInt(next());
    }
    
    public long nextLong() {
        return Long.parseLong(next());
    }
    
    public double nextDouble() {
        return Double.parseDouble(next());
    }
    
    public String next() {
        try {
            while (!st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return st.nextToken();
        }
    }
    
}