Editorial for Mock CCC '19 Contest 1 J2 - Pusheen OCR
Submitting an official solution before solving the problem yourself is a bannable offence.
For 14 marks, your program can check the characters in the string from left to right. The moment it detects a character that is incorrect, it knows that all the characters after that one will be incorrect, and it can print the answer directly.
For full credit, it suffices to check every character manually. This solution may be easier for people to implement than the above solution, which is a reminder that sometimes it is easier to solve the problem in its entirety than to immediately go for a subtask.