def int_to_alphabet(n)
    ('A'..'Z').to_a[n]
end

def alphabet_to_int(n)
    /#{n}/ =~ ('A'..'Z').to_a.join
end


before = gets.chomp.split("")

count = 1
after = []
before.each do |n|
    after_num = alphabet_to_int(n) - count
    while after_num < 0
        after_num += 26
    end
    count += 1
    after.push(int_to_alphabet(after_num))
end

puts after.join