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.

Ex Input:
Sentence1: Jennifer went out that morning to walk the dog. Sentence2: He was a very excitable labrador retriever. Sentence3: Jennifer did not see the bunny until it was too late. Sentence4: Fido bounded after it, while she raced to keep up. Sentence5: She was finally able to slow him down, and make him stop chasing it.

Ex Output:
Bunny, Jennifer

Ex Input:
Sentence1: Zack was always worried about getting sick. Sentence2: And he became so worried about the air that he wore a respirator. Sentence3: He wore it during his entire school day. Sentence4: And he told other students that the air quality was terrible. Sentence5: Zack still ended up getting sick and worried much more.

Ex Output:
Other students, Zack

Ex Input:
Sentence1: Bill had a bad cold. Sentence2: He scheduled a doctor's appointment. Sentence3: The doctor examined him. Sentence4: Bill received a prescription for some strong cold medicine. Sentence5: Soon, Bill felt much better.

Ex Output:
Doctor, Bill