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: Ken was a cook. Sentence2: Ken was given an order for a medium rare steak. Sentence3: Ken cooked up the steak nice and rare. Sentence4: He went to serve it to the customers. Sentence5: The customer told him they wanted it well done.

Ex Output:
Customer, Ken, Customers

Ex Input:
Sentence1: Simon didn't like anyone and no one liked him either. Sentence2: He was mean and liked to hurt little animals. Sentence3: One day, a young boy went to him with a frog. Sentence4: Simon took the frog and was about to hurt it when the boy screamed. Sentence5: Simon was so touched, he put the frog on the ground and left.

Ex Output:
Boy, Simon, Frog

Ex Input:
Sentence1: John wanted to learn how to play the violin. Sentence2: He went to the music store to buy one. Sentence3: He selected a cheap model that he thought would do for a beginner. Sentence4: He started practicing and two strings broke right away. Sentence5: John went back to the store and bought a better violin.

Ex Output:
John