First, the code you provided "works" in Python 2.7 and 3.
A line number or stacktrace would be helpful, but assuming it's in the snippet you provided:
nota = int(input("Que nota recebeu: "))
Here nota is an int.
if len(str(nome).strip()) == 0:
The next line you're trying to cast it to a string without specifying how.
Something like:
if len(("%d" % nota).strip()) == 0:
should prevent the error.
That being said, the line still makes little sense. You shouldn't have to strip() a string representation of an integer.
What are you trying to accomplish with strip() and the if len(...) == 0 parts?
Edit: Lastly, I think you want raw_input() instead of input(), unless you're shadowing that somewhere too.
'1' + 1-->TypeError: Can't convert 'int' object to str implicitly, so check your code for such mistakes.