Python: I have a python statement that should work but it does not work

The error in the image is highlighted in red.

So, I used this code on another computer and it worked, why does not it work now? You may have made a really small and stupid mistake and, if I'm sorry, I'm sorry I wasted my time, but it should work. By the way, this is only done to run in the python shell and is not supposed to have graphics except text.

For a bit of context, this is used at the beginning of the game that I am creating and used to determine the level of difficulty.

If this is not supposed to work, but there is an alternative, I would appreciate the help.

enter the description of the image here

All the help, comments and answers are appreciated.