from sys import stdin
from random import randint
from collections import deque, defaultdict as dd
from copy import deepcopy
input = stdin.readline
MOD = 998244353
INF = 1 << 60
xor = randint(100, INF)


def extended_gcd(a, b):
    if b == 0:
        return a, 1, 0
    else:
        g, x, y = extended_gcd(b, a % b)
        return g, y, x - (a // b) * y


def mod_inverse(a, m):
    _, x, _ = extended_gcd(a, m)
    return (x % m + m) % m


def fast_mod_pow(x, p):
    res = 1
    t = x
    z = p
    while z > 0:
        if z % 2 == 1:
            res = (res * t)
        t = (t * t)
        z //= 2
    return res


def main():
    n, k = map(int, input().split())
    p = [tuple(map(float, input().split()))for _ in range(n)]
    dist = [[0.for _ in range(n)]for _ in range(n)]
    for i in range(n):
        for j in range(n):
            x1, y1 = p[i]
            x2, y2 = p[j]
            dist[i][j] = ((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))**0.5
    central = [0.]*n
    for i in range(n):
        x, y = p[i]
        central[i] = (x*x+y*y)**0.5
    dp = [[[1e60for _ in range(k)] for _ in range(n)]for _ in range(1<<n)]
    for i in range(n):
        dp[1<<i][i][0] = central[i]
    for bit in range(1<<n):
        for i in range(n):
            for j in range(k):
                for nex in range(n):
                    shift = 1<<nex
                    if bit & shift: continue
                    nf = bit | shift
                    dp[nf][nex][0] = min(dp[nf][nex][0], dp[bit][i][j]+central[i]+central[nex])
                    if j < k-1:
                        dp[nf][nex][j+1] = min(dp[nf][nex][j+1], dp[bit][i][j]+dist[i][nex])
    ans = 1e60
    for i in range(n):
        for j in range(k):
            ans = min(ans, dp[(1<<n)-1][i][j]+central[i])
    print(ans)



if __name__ == "__main__":
    main()