class Present
  attr_reader :l, :w, :h

  def initialize(l, w, h)
    @l = l
    @w = w
    @h = h
  end

  def self.for(string)
    new *string.split("x").map(&:to_i)
  end

  def paper
    surface_area + slack
  end

  def side_areas
    [l*w, l*h, w*h]
  end

  def surface_area
    side_areas.sum * 2
  end

  def slack
    side_areas.min
  end

  def perimeters
    [2*(l+w), 2*(l+h), 2*(w+h)]
  end

  def volume
    l*w*h
  end

  def ribbon
    perimeters.min + volume
  end
end