Wait, what? Hold on a tick. Divide by 4?
If you just want the number of lists, then use the len function...
That will give you 3 in my example.
And in the code you posted, don't do:
Reassign your array in the same manner I showed you in my second post.
x = x[a:] # Will keep all elements from the a'th element to the end
x = x[:a] # Will keep all elements until the a'th element