#!/usr/bin/env pypy3

import collections
import itertools
import math


class Vector3(collections.namedtuple("Vector3", "x y z")):

    __slots__ = ()

    def __add__(self, other):
        return Vector3(*(s + o for s, o in zip(self, other)))

    def __sub__(self, other):
        return Vector3(*(s - o for s, o in zip(self, other)))

    def __mul__(self, other):  # cross product
        m1 = self.y * other.z - self.z * other.y
        m2 = self.z * other.x - self.x * other.z
        m3 = self.x * other.y - self.y * other.x
        return Vector3(m1, m2, m3)

    def __neg__(self):
        return Vector3(-self.x, -self.y, -self.z)

    def __pos__(self):
        return Vector3(+self.x, +self.y, +self.z)

    def __abs__(self):  # norm
        return math.sqrt(sum(s * s for s in self))

    def dotproduct(self, other):
        return sum(s * o for s, o in zip(self, other))

    def angle(self, other):
        return math.acos(self.dotproduct(other) / abs(self) / abs(other))

    def scale(self, k):
        return Vector3(k * self.x, k * self.y, k * self.z)


def dist(q1, q2, q3):
    v1 = q2 - q1
    v2 = q3 - q2
    cp = v1 * v2
    return abs(q1.dotproduct(cp)) / abs(cp)


def solve(p, qs):
    return sum(dist(*q123) for q123 in itertools.combinations(qs, 3))


def main():
    n = int(input())
    p = Vector3(*map(float, input().split()))
    qs = [Vector3(*map(float, input().split())) - p for _ in range(n)]
    print("{:.12f}".format(solve(p, qs)))


if __name__ == '__main__':
    main()