Ruby(HardWay(ex9)) << uninitialized constant PARAGRAPH-Collection of common programming errors

I’m doing Ruby the Hard Way (ex9) -> http://ruby.learncodethehardway.org/book/ex9.html

Why can it not find the constant PARAGRAPH?

ERROR =>:

$ ruby ex9.rb
ex9.rb:9: uninitialized constant PARAGRAPH (NameError)

CODE (my input):

# Here's some new strange stuff, remember type it exactly.

days = "Mon Tue Wed Thu Fri Sat Sun"
months = "Jan\n\Feb\nMar\nApr\nMay\nJun\nJul\nAug"

puts = "Here are the days: ", days
puts = "Here are the months: ", months

puts