the switch structure doesnt allow a range to be represented in that way.
Note - in specifying a range you must use this exact format
case (low value) space three dots space (high value): as shown above.
I'm sure if you delete all but the first case it will still show a compiler error.
You DONT need to have a "default " if the cases cover all possibilities - but in your case if d can exceed 25 its better to have one.