Bob, Rob, and Robert live on the six hundredth floor of an apartment building. One day, the elevators are broken, so they have to take the stairs. To entertain themselves, they decide that for the first 200 floors, Bob will tell happy stories, for the middle 200 floors, Rob will tell funny stories, and for the last 200 floors, Robert will tell sad stories. On the 401st floor, Robert says, "Here's my sad story: I left our apartment's keys in the car."
