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: Julia was looking for her very favorite blouse. Sentence2: When she didn't find it she went to ask her sister. Sentence3: To her surprise her sister was wearing the shirt. Sentence4: She refused to take it off and Julia attacked her. Sentence5: Their dad broke it up and took the shirt away for good.

Ex Output:
Dad, Sister, Julia

Ex Input:
Sentence1: Jim was sledding with his friend Anthony. Sentence2: Anthony dared him to go down the big hill. Sentence3: Jim took up the dare and as he was going he fell out of the sled. Sentence4: Jim rolled a few times as the unmanned sled flew into the river. Sentence5: Jim was ok, and the two of them went home for the day.

Ex Output:
Anthony, Jim

Ex Input:
Sentence1: Chuck was hanging out with some friends at a bar. Sentence2: They mentioned that they were moving soon. Sentence3: Chuck offered to help them move their things. Sentence4: The team worked together and got the move done quickly. Sentence5: They were so grateful that they invited him to stay for dinner.

Ex Output:
Chuck, Friend