In how many ways can 8 examination papers be arranged in a line so that the best and worst papers are never together ?

Let us assume the question papers to be a,b,c,d,e,f,g,h. where all are different and a and h are the best and worst respectively.
The total number of arrangements = 8! 
We then need to find the no of arrangements when a and h occur together = 7! * 2!
Now, the number of arrangements when a and h don't occur together = 8! - (7!*2!)
=30240