n,k = map(int,input().split())
xy = [tuple(map(int,input().split())) for _ in range(n)]+[(0,0)]
dp = [[[10**18]*(k+1) for _ in range(n+1)] for _ in range(1<<n)]
dp[0][n][k] = 0
for s in range(1<<n):
    for i in range(n+1):
        if i<n and s>>i&1==0: continue
        xi,yi = xy[i]
        for j in range(n+1):
            xj,yj = xy[j]; d = ((xi-xj)**2+(yi-yj)**2)**0.5
            if j<n:
                if s>>j&1==1: continue
                for l in range(k):
                    t = s^1<<j
                    dp[t][j][l] = min(dp[t][j][l],dp[s][i][l+1]+d)
            else:
                for l in range(k):
                    dp[s][j][k] = min(dp[s][j][k],dp[s][i][l]+d)
print(dp[-1][-1][-1])