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.

Input: Consider Input: Sentence1: Tre's bicycle really needed new brakes. Sentence2: Tre saved up all his allowance to take his bike to the shop. Sentence3: On the way a teenager jumped Tre and stole all his money and his bike. Sentence4: Tre walked home crying and empty handed. Sentence5: When he got there he found his mother dead.

Output: A teenager, His mother, Tre

Input: Consider Input: Sentence1: Jim designed a fun game website in his spare time. Sentence2: He shared it with some friends, and it became popular. Sentence3: One morning Jim woke to a message in his inbox. Sentence4: A major company wanted to buy Jim's site for $15 million! Sentence5: Jim was overjoyed!

Output: Company, Jim, Friends

Input: Consider Input: Sentence1: Polly loved cats. Sentence2: She didn't have a cat and wanted to adopt one. Sentence3: Polly learned that a friend of hers was fostering kittens. Sentence4: Polly went to her friend's house and met all the kittens there. Sentence5: She bonded with two of them and adopted them on the spot!
Output: Polly, Friend, Kittens