I'm learning to write Ruby using classes (as opposed to scripts).
I can't get the following (extremely simple) class to run (although I
get the corresponding script right). What do I need to do to fix it?

Here is the class:

class Input1

  def initialize(n1, n2)
    @n1 = n1
    @n2 = n2
  end

  def sum
    @n1 + @n2
  end

end

puts "Enter first number: "
@n1 = gets
puts "Enter second number: "
@n2 = gets

puts result = Input1(new).sum.to_s