booklet page generator

#!/bin/ruby

unless ARGV.length > 0
  puts "You must specify a number of pages."
  return -1
end

num_pages = ARGV.first.chomp.to_i

remainder = num_pages % 4
num_pages += 4 - remainder unless remainder == 0

output = ""
count = 0

(num_pages / 4).times do
  output += "#{num_pages - count},"
  output += "#{1 + count},"
  count += 1
  output += "#{1 + count},"
  output += "#{num_pages - count},"
  count += 1
end

puts "#{num_pages} pages are required for a booklet. Print them in this order #{output}"