A boy owned a dog that was uncommonly shaggy. He was quite shaggy at two and twice a shaggy at four. Many people remarked upon its considerable shagginess. He is five years old today and very shaggy. When the boy learned that there are contests for shaggy dogs, he entered his dog. The dog won first prize for shagginess in both the local and the regional competitions. The boy entered the dog in ever-larger contests, until finally he entered it in the world championship for shaggy dogs. When the judges had inspected all of the competing dogs, they remarked about the boy's dog: "He's not that shaggy." How old was the dog three years ago?