prime orz

prime.rb

#!/usr/bin/env ruby

@INPUT = ARGV[0].to_i
if @INPUT == nil then
  puts '[usage] ex) ruby prime.rb 5'
  exit
end

(2..Math.sqrt(@INPUT)).each do |i|
  if @INPUT % i == 0 then
    puts 'false'
    exit 0
  end
end

puts 'true'