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: My science class took a field trip to the bio park today. Sentence2: Only about half of the students were allowed to go on the trip. Sentence3: My best friend Mark got left behind because he failed a math test. Sentence4: That doesn't seem fair to me because he is really good at science. Sentence5: I don't understand why teachers punish students who really try hard.

Ex Output:
Students, I (myself), Teachers, Mark

Ex Input:
Sentence1: Susie was having a costume party. Sentence2: She invited all of her friends. Sentence3: She dressed up as a cat. Sentence4: Her friends loved it. Sentence5: Susie ended up winning the costume contest at the party.

Ex Output:
Susie, Her friends

Ex Input:
Sentence1: A third base coach gave the wrong sign to a player on first. Sentence2: The player ran to steal second base and was almost thrown out. Sentence3: The coach felt in the moment so he told the player to steal again. Sentence4: Once again the player tried to steal a base but was thrown out. Sentence5: That was the third out and the inning was over.

Ex Output:
Player, Coach