class RPNCalculator
  def initialize
    @calculator = []
  end

  def push(num)
    @calculator << num
  end

  def plus
    @calculator << @calculator.pop + @calculator.pop
  end
  def times
    @calculator << @calculator.pop * @calculator.pop
  end
  def minus
    @calculator << -1 * @calculator.pop + @calculator.pop
  end
  def divide
    @calculator << (1 / @calculator.pop.to_f) * @calculator.pop
  end
  def value
    @calculator.last
  end

end