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
    now = 'Z' unless 'A' <= now && now <= 'Z'
  end
  s = s.sub(i, now)
end

puts s