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: Joe was bit by a cat when he was very young. Sentence2: Since then, he has always been scared of cats. Sentence3: One day at school, a cat came up to him and played with him. Sentence4: Joe had a lot of fun with the cat. Sentence5: Now, Joe is not scared of cats.

Ex Output:
Joe, Cat

Ex Input:
Sentence1: Bob's bought a trailer that had a shingle roof. Sentence2: When it rained the roof would leak pretty badly. Sentence3: Bob checked his insurance policy to see if it was covered. Sentence4: The insurance replaced the shingle roof with a metal one. Sentence5: Bob's happy the rain doesn't leak into his house any more.

Ex Output:
Bob

Ex Input:
Sentence1: Sally had to move from one city to another with her parents. Sentence2: She was sad to leave all of her friends behind. Sentence3: When Sally went to her new school she was very nervous and afraid. Sentence4: Sally had a hard time making friends at first. Sentence5: After a while Sally eventually made new friends and was happy again.

Ex Output:
Friends, Sally, Parents