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: When I was 6 years old, a dog followed me home from school. Sentence2: This dog became my best friend of all time. Sentence3: Her breed was a Boxer, which is a protective, family oriented dog. Sentence4: Unfortunately, someone stole her from our backyard when I was 12. Sentence5: I will always wonder what happened to Gertrude the Boxer dog.
A:
I (myself), The dog, Someone