import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

class Point:
    def __init__(self, x, y, z):
        self.x=x
        self.y=y
        self.z=z
    def __add__(self, other):
        return Point(self.x+other.x, self.y+other.y, self.z+other.z)
    def __sub__(self, other):
        return Point(self.x-other.x, self.y-other.y, self.z-other.z)
    def __mul__(self, other):
        return Point(self.x*other, self.y*other, self.z*other)
    def dot(self, other):
        return self.x*other.x+self.y*other.y+self.z*other.z
n=int(readline())
px, py, pz=map(float, readline().split())
p=Point(px, py, pz)
xyzs=list(map(float, read().split()))
xs=xyzs[::3]
ys=xyzs[1::3]
zs=xyzs[2::3]
qs=[Point(x, y, z) for x, y, z in zip(xs, ys, zs)]
import itertools, math
ans=0
for q1, q2, q3 in itertools.combinations(qs, 3):
    a, b, c=q1-p, q2-q1, q3-q1
    ab, ac, bb, bc, cc=a.dot(b), a.dot(c), b.dot(b), b.dot(c), c.dot(c)
    d=bb*cc-bc*bc
    s=(-cc*ab+bc*ac)/d
    t=(bc*ab-bb*ac)/d
    e=a+b*s+c*t
    ans+=math.sqrt(e.dot(e))
print('{:.10f}'.format(ans))