#!/usr/bin/env pypy3

import collections
import functools
import itertools
import math
import operator


# Based on http://thira.plavox.info/blog/2008/06/_c.html
def in_place_det(a):
    n = len(a)
    for i, j in itertools.product(range(n), repeat=2):
        if i < j:
            b = a[j][i] / a[i][i]
            for k in range(n):
                a[j][k] -= a[i][k] * b
    d = functools.reduce(operator.mul, (a[i][i] for i in range(n)))
    return d


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
        return abs(self) * abs(other) * math.sin(self.angle(other))

    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 volume_of_trigonal_pyramid(p, q1, q2, q3):
    v1 = q1 - p
    v2 = q2 - p
    v3 = q3 - p
    a = [list(v1), list(v2), list(v3)]
    return abs(in_place_det(a) / 6)


def volume_of_triangle(q1, q2, q3):
    a = q2 - q1
    b = q3 - q1
    return abs(a * b) / 2


def dist(p, q1, q2, q3):
    d = volume_of_trigonal_pyramid(p, q1, q2, q3) * 3
    d /= volume_of_triangle(q1, q2, q3)
    return d


def solve(p, qs):
    return sum(dist(p, *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())) for _ in range(n)]
    print("{:.12f}".format(solve(p, qs)))


if __name__ == '__main__':
    main()