import sys
input = sys.stdin.readline

N,K=map(int,input().split())
P=[list(map(int,input().split())) for i in range(N)]

DP=[[1<<60]*(1<<N) for i in range(N)]

DIS=[[0]*N for i in range(N)]

for i in range(N):
    for j in range(N):
        x,y=P[i]
        z,w=P[j]

        DIS[i][j]=((x-z)**2 + (y-w)**2)**(1/2)

D=[0]*N

for i in range(N):
    x,y=P[i]
    D[i]=(x**2+y**2)**(1/2)

for i in range(N):
    DP[i][1<<i]=D[i]

for i in range(N):
    for j in range(1<<N):

        for k in range(N):
            if j & (1<<k) != 0:
                continue

            to=j | (1<<k)

            if to.bit_count()>K:
                continue

            DP[k][to]=min(DP[k][to],DP[i][j]+DIS[i][k])

DIS_COME=[1<<60]*(1<<N)

for i in range(N):
    for j in range(1<<N):
        DIS_COME[j]=min(DIS_COME[j],DP[i][j]+D[i])

if N==K:
    print(DIS_COME[-1])
    exit()

DP2=[1<<60]*(1<<N)
DP2[0]=0


# 3^NのDP（部分集合を列挙）

for i in range(1<<N):
    p=i
    while p!=0:
        p=(p-1) & i

        DP2[i]=min(DP2[i],DIS_COME[p]+DIS_COME[p^i])

print(DP2[-1])