Multiple check boxes with a NOT applicable box

Basically, as seen here, I've run into a bit of a hiccup with the form. I want the person filling it out to be able to multi select "morning/afternoon/evening" but if "not applicable" is selected, I want the checks in the other boxes to be erased. I am assuming it has to be a script to do so, I just don't know how, and I can't seem to find the answer here or on an internet search.
