N,K=list(map(int,input().split()))
M=[]
def dist(i,j):
  return ((M[i][0]-M[j][0])**2+(M[i][1]-M[j][1])**2)**(0.5)
for i in range(N):
  x,y=list(map(int,input().split()))
  M.append((x,y))
M.append((0,0))
dp=[]
for i in range(N+1):
  p=[]
  for k in range(K+1):
    p.append([10**18]*(2**N))
  dp.append(p)
dp[N][K][0]=0#dp[どこにいるかNならピザや][何枚あるか][どこ尋ねたか]
for i in range(2**N):
  for j in range(N+1):
    for k in range(K+1):
      if j!=N:
        if k==0:
          dp[N][K][i]=min(dp[N][K][i],dp[j][k][i]+dist(j,N))
        else:
          dp[N][K][i]=min(dp[N][K][i],dp[j][k][i]+dist(j,N))
          for l in range(N):
            if 2**j&i!=0 and 2**l&i==0:
              dp[l][k-1][i|2**l]=min(dp[l][k-1][i|2**l],dp[j][k][i]+dist(j,l))
      else:
        for l in range(N):
          if 2**l&i==0:
            dp[l][k-1][i|2**l]=min(dp[l][k-1][i|2**l],dp[j][k][i]+dist(j,l))
print(dp[N][K][2**N-1])