def decode(char, index)
  list = ("A".."Z").to_a
  list[(list.index(char) - index) % 26]
end

# # pp decode("K", 3)
# # pp decode("A", 3)
# pp decode("A", 24)


S = gets.chomp

puts S.chars.map.with_index(1) { |c, i| decode(c, i) }.join