Detailed Instructions: In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Q: Sentence1: Jack bought a new book yesterday. Sentence2: He placed the book on the couch when he got home from the bookstore. Sentence3: Jack didn't see his dog in the living room. Sentence4: When Jack went to lunch, his dog tore the book apart. Sentence5: Jack wished he had placed his book in a better spot.
A:
Jack, Dog