Answer 1

Your code works absolutely fine.

Just split it in multiple lines like
12
13

And this will work.

Answer 2

There's no error in ur code.
As EnCoDeR told Split the input.
That is for eg: type 1st input, then hit enter, then type the 2nd input and Submit. That's it.

https://code.sololearn.com/ctJY81hfl1ip/?ref=app

Answer 3

Are you sure you gave the correct input? See here how input is handled on SoloLearn

https://code.sololearn.com/WhiNb9BkJUVC/?ref=app