#!/usr/bin/env ruby

regex = /[a-z0-9A-Z]+/

replace = ARGV[0] || 'crap'

needle = 0

upper_case_chars = ('A'..'Z').to_a

STDIN.each_char do |char|
  if char =~ regex
    if upper_case_chars.include?(char)
      print replace[needle].upcase
    else
      print replace[needle]
    end
    needle += 1
    if needle == replace.size
      needle = 0
    end
  else
    print char
  end
end