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: Tim's friend always visited when it town. Sentence2: He always waited until the last minute to announce his arrival. Sentence3: Tim got annoyed by that after a while. Sentence4: Soon Tim stopped hanging out with the friend as much. Sentence5: Eventually the friend stopped inviting instead.

Ex Output:
Tim, Tim's friend

Ex Input:
Sentence1: When Poppy was growing up, she had a very special doll. Sentence2: She took the doll with her everywhere. Sentence3: As she got older, her mother tried to make her give up the doll. Sentence4: Poppy hid the doll so her mother couldn't find it. Sentence5: But Poppy's dog found the doll and chewed it to pieces.

Ex Output:
Poppy, Dog, Mother

Ex Input:
Sentence1: Chris was worried about going to school. Sentence2: There was a boy that constantly bullied Chris there. Sentence3: Chris went to school in anticipation of a fight. Sentence4: He couldn't believe his eyes when he walked by the principal's office. Sentence5: The bully was in the principal's office crying with his mother there!

Ex Output:
Chris, His mother, Principals, The boy, Principal