import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

def norm(i, j):
    x, y = xy[i]
    p, q = xy[j]
    return ((x-p)**2+(y-q)**2)**0.5

n, k = LI()
xy = LLI(n)
dist = [[[inf]*k for _ in range(n)] for _ in range(1<<n)]
hp = []
for i, (x, y) in enumerate(xy):
    s = 1 << i
    d = (x**2+y**2)**0.5
    dist[s][i][k-1]=d
xy.append([0, 0])
ans=inf
for s in range(1,1<<n):
    for i in range(n):
        for r in range(k):
            d=dist[s][i][r]
            if d==inf:continue
            for j in range(n):
                if s >> j & 1: continue
                ns = s | 1 << j
                nd = d+norm(i, n)+norm(j, n)
                if nd < dist[ns][j][k-1]:
                    dist[ns][j][k-1] = nd
                if r:
                    nd = d+norm(i, j)
                    if nd < dist[ns][j][r-1]:
                        dist[ns][j][r-1] = nd

for i in range(n):
    for r in range(k):
        ans=min(ans,dist[-1][i][r]+norm(i,n))
print(ans)