Found an interesting bug(or feature?):

When I tried to solve the problem using the following code it gives me Wrong answer

Code (Python 3), Verdict: Wrong Answer

s = input()
s_sorted = sorted(s,key = lambda x:(x.isdigit() and int(x)%2==0, x.isdigit(),x.isupper(),x.islower(),x))
print(*(s_sorted),sep = '')

Like the problem said:

 a) Using join, for or while anywhere in your code, even as substrings, will result in a score of 0. b) You can only use sorted function in your code. A 0 score will be awarded for using sorted more than once.

But in the above code I did not use join, for or while. Also I did not use sorted() more than once!

What I realized later that it is counting the variable s_sorted as sorted() function. So, I removed _sorted and it got Accepted.

Code (Python 3), Verdict: Accepted

s = input()
s = sorted(s,key = lambda x:(x.isdigit() and int(x)%2==0, x.isdigit(),x.isupper(),x.islower(),x))
print(*(s),sep = '')

Funny, right? :D