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;gets.split.map(&:to_f)end
def cross(a,b)
[a[1]*b[2]-a[2]-b[1],a[2]*b[0]-a[0]*b[2],a[0]*b[1]-a[1]*b[0]]
end
n=gets.to_i
p=Vector[*g]
q=(1..n).map{Vector[*g]}
sum=0
q.combination(3){|a,b,c|
  t=(b-a).outer_product(c-a)
  sum+=(p.inner_product(t)-a.inner_product(t)).abs/t.norm
}
p sum