Hello, I used the following code for 5:

```
def factorial(x):
if x==0:
return 1
else:
a=1
z=1
while a<=x:
z *= a
a+=1
return z
```

and this is showing not valid without an error sign. I put the same code (except for changing return to print and and getting input prompt) in repl.it as below:

```
def factorial(x):
if x==0:
print 1
else:
a=1
z=1
while a<=x:
z *= a
a+=1
print z
factorial(int(raw_input()))
```

and it seems to give the correct answers for all positive integers. Thank you in advance.