Statement

Marco's phone has been attacked by hackers with a ransomware: they have remotely encrypted the phone book with all his contacts and now he has been asked to pay a ransom in bitcoins to recover his data. He has decided to have some fun trying to perform a full reverse engineering of the malware to recover data without having to pay money. Fortunately for him, the encryption scheme is not too sophisticated. The malware encrypts each digit in isolation and substitutes it with a code. For every digit from 0 to 9, Marco has been able to determine which was the corresponding code. For instance, suppose that digit 0 hash been replaced with the code 12345 and that the digit 1 has been replaced with the code 1235; in this scenario an hypothetical number 010 would have been encrypted with the sequence of digits 12345123512345. After all this grueling work, Marco asks you a small help: recover the original unencrypted numbers for his N contacts in the phone book.