#![allow(dead_code)]
#![allow(unused_imports)]
#![allow(unused_macros)]

use std::cmp::*;
use std::fmt::*;
use std::hash::*;
use std::io::BufRead;
use std::iter::FromIterator;
use std::*;
use std::{cmp, collections, fmt, io, iter, ops, str};
const INF: i64 = 1223372036854775807;
const UINF: usize = INF as usize;
const LINF: i64 = 2147483647;
const INF128: i128 = 1223372036854775807000000000000;
const MOD1: i64 = 1000000007;
const MOD9: i64 = 998244353;
const MOD: i64 = MOD9;
const UMOD: usize = MOD as usize;
const M_PI: f64 = 3.14159265358979323846;

use cmp::Ordering::*;
use std::collections::*;

use std::io::stdin;
use std::io::stdout;
use std::io::Write;

macro_rules! p {
    ($x:expr) => {
        println!("{}", $x);
    };
}

macro_rules! vp {
    ($x:expr) => {
        println!(
            "{}",
            $x.iter()
                .map(|x| x.to_string())
                .collect::<Vec<_>>()
                .join(" ")
        );
    };
}

macro_rules! d {
    ($x:expr) => {
        eprintln!("{:?}", $x);
    };
}
macro_rules! yn {
    ($val:expr) => {
        if $val {
            println!("Yes");
        } else {
            println!("No");
        }
    };
}

macro_rules! map{

    ($($key:expr => $val:expr),*) => {
        {
            let mut map = ::std::collections::BTreeMap::new();
            $(
                map.insert($key, $val);
            )*
            map
        }
    };
}

macro_rules! set{

    ($($key:expr),*) => {
        {
            let mut set = ::std::collections::BTreeSet::new();
            $(
                set.insert($key);
            )*
            set
        }
    };
}

#[allow(dead_code)]
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

#[allow(dead_code)]
fn read_mat<T: std::str::FromStr>(n: usize) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}

#[allow(dead_code)]
fn readii() -> (i64, i64) {
    let mut vec: Vec<i64> = read_vec();
    (vec[0], vec[1])
}

#[allow(dead_code)]
fn readiii() -> (i64, i64, i64) {
    let mut vec: Vec<i64> = read_vec();
    (vec[0], vec[1], vec[2])
}
#[allow(dead_code)]
fn readuu() -> (usize, usize) {
    let mut vec: Vec<usize> = read_vec();
    (vec[0], vec[1])
}

#[allow(dead_code)]
fn readff() -> (f64, f64) {
    let mut vec: Vec<f64> = read_vec();
    (vec[0], vec[1])
}

fn readcc() -> (char, char) {
    let mut vec: Vec<char> = read_vec();
    (vec[0], vec[1])
}

fn readuuu() -> (usize, usize, usize) {
    let mut vec: Vec<usize> = read_vec();
    (vec[0], vec[1], vec[2])
}
#[allow(dead_code)]
fn readiiii() -> (i64, i64, i64, i64) {
    let mut vec: Vec<i64> = read_vec();
    (vec[0], vec[1], vec[2], vec[3])
}

#[allow(dead_code)]
fn readuuuu() -> (usize, usize, usize, usize) {
    let mut vec: Vec<usize> = read_vec();
    (vec[0], vec[1], vec[2], vec[3])
}

fn dist(a: (f64, f64), b: (f64, f64)) -> f64 {
    ((a.0 - b.0).powi(2) + (a.1 - b.1).powi(2)).sqrt()
}
fn main() {
    let (n, k) = readuu();
    let mut pos = vec![];
    for i in 0..n {
        let (x, y) = readii();
        pos.push((x as f64, y as f64));
    }
    let mut dp = vec![vec![vec![UINF as f64; 1 << n]; n]; k];
    for i in 0..n {
        dp[k - 1][i][1 << i] = dist((0.0, 0.0), pos[i]);
    }
    for b in (0..(1 << n)) {
        for i in 0..n {
            if b & (1 << i) == 0 {
                continue;
            }
            for j in 0..n {
                if b & (1 << j) != 0 {
                    continue;
                }

                for l in 0..k {
                    dp[k - 1][j][b | (1 << j)] = dp[k - 1][j][b | (1 << j)]
                        .min(dp[l][i][b] + dist((0.0, 0.0), pos[i]) + dist((0.0, 0.0), pos[j]));
                    if l == 0 {
                        continue;
                    }
                    dp[l - 1][j][b | (1 << j)] =
                        dp[l - 1][j][b | (1 << j)].min(dp[l][i][b] + dist(pos[i], pos[j]));
                }
            }
        }
    }
    let mut ans = INF as f64;
    for i in 0..n {
        for j in 0..k {
            ans = ans.min(dp[j][i][(1 << n) - 1] + dist((0.0, 0.0), pos[i]));
        }
    }
    //debug
    // for i in 0..n {
    //     for j in 0..k {
    //         for l in 0..(1 << n) {
    //             eprint!("{} ", dp[j][i][l]);
    //         }
    //         eprintln!();
    //     }
    // }

    println!("{}", ans);
}