s = gets.not_nil!.chomp

s.each_char_with_index do |char, i|
  now = char
  (1..(i + 1)).each do
    now = (now.ord - 1).chr
    if !('A'..'Z').includes?(now)
      now = 'Z'
    end
  end
  s = s.sub(i, now)
end

puts s