|시간 제한||메모리 제한||제출||정답||맞은 사람||정답 비율|
|2 초||512 MB||10||9||9||90.000%|
John likes simple ciphers. He had been using the “Caesar” cipher to encrypt his diary until recently, when he learned a hard lesson about its strength by catching his sister Mary browsing through the diary without any problems.
Rapidly searching for an alternative, John found a solution: the famous “Autokey” cipher. He uses a version that takes the 26 lower-case letters ‘a’–‘z’ and internally translates them in alphabetical order to the numbers 0 to 25.
The encryption key k begins with a secret prefix of n letters. Each of the remaining letters of the key is copied from the letters of the plaintext a, so that kn+i = ai for i ≥ 1. Encryption of the plaintext a to the ciphertext b follows the formula bi = ai + ki mod 26.
Mary is not easily discouraged. She was able to get a peek at the last n letters John typed into his diary on the family computer before he noticed her, quickly encrypted the text document with a click, and left. This could be her chance.
The input consists of:
Output the plaintext of John’s diary.
5 16 again pirpumsemoystoal
1 12 d fzvfkdocukfu