Slightly optimized answer

Hey, I just changed your line 8 and 9 to do the exact same thing but be a little neater. ^^ 

Oh! and if you want it might not be a bad idea to change your naming system to:

- Problem001.py
- Problem002.py
- Problem010.py
- Problem123.py

etc.. Currently the way you have it set up it looks like:
- Problem 1.py
- Problem 10.py
- Problem 112.py
- Problem 12.py
- Problem 2.py

And so on which makes it a little harder for an outsider to quickly find your code (or yourself even!)

Anyway, feel free to deny the merge, I just wanted to stop by and leave a comment just in case though. Have a nice day. :)