Cycle through the following operations one at a time until no further operations can be performed:

1. If the string prefix is 'aa', remove the first character.
2. If the string ends with 'aa', replace it with 'cc'.
3. If the string prefix is 'ca', replace it with 'bb' and append 'c' to the end.
4. If the string suffix is 'cc', replace it with 'b' and prepend 'a' to the start.
5. If the string suffix is 'bb', delete the last two characters.
6. If the string ends with 'ca', remove the last character.

For the string "aabccbccbbccbb", what is the final string after performing all operations?

Provide your answer as a string in the following format:

<<< "some_final_string" >>>
