I'm currently attempting to create a function that adds 1 to the value that's in the middle of the list.

```
Example: (add1 '(2 4 6 5 9)) -> (2 4 7 5 9)

```

Also if the list is even, it returns nothing. So far I have a function that returns the location of the middle of the list.

```
(defun add1(aList)
               (if (oddp (length aList)) (- (/ (length aList) 2) .5) 'EvenNumber))

```

Example: (add1 '(2 4 6 5 9)) -> 2.0

Is there a way to use this information to get to the value in the middle then add 1 to it. Thanks