require 'matrix'
class Vector
  def outer_product(o)
    raise 'outer_product is size3 only(size#{self.size})' unless size == 3
    Vector[
      self[1]*o[2]-self[2]*o[1],
      self[2]*o[0]-self[0]*o[2],
      self[0]*o[1]-self[1]*o[0],
    ]
  end
end
def g;Vector[*gets.split.map(&:to_f)]end
n=gets.to_i
P=g
p((1..n).map{g-P}.combination(3).map{|a,b,c|
  t=(b-a).outer_product(c-a)
  a.inner_product(t).abs/t.norm
}.inject(:+))