I'm having troubles with the factorial exercise:

https://www.codecademy.com/courses/python-intermediate-en-rCQKw/0/5?curriculum_id=4f89dab3d788890003000096

It calculates the factorial correctly (a 24 for x=4, a 120 for x=5, etc...) but then I get this error:

Oops, try again. factorial(1) resulted in an error: invalid literal for int() with base 10: ''

Any idea on why this keeps happening? Thanks in advance.

```
def factorial(x):
x=int(raw_input("Number?")) #Number
f=x #Factorial
while x > 1:
x=x-1
f=f*x
print "The factorial is" , f
return f
factorial(x)
```