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: Sam had a big exam for an important college course. Sentence2: He studied hard and went to every class. Sentence3: On the day of the exam he noticed the room was empty. Sentence4: The time and location had been changed. Sentence5: He never bothered to check his email and didn't know.

Output: Sam

Input: Consider Input: Sentence1: Susie and her friends decided to play graveyard. Sentence2: The girls laid down on the field motionless. Sentence3: All the sudden Susie moved. Sentence4: She ended up losing the game first. Sentence5: Susie laughed but wanted to play again.

Output: Friends, Susie

Input: Consider Input: Sentence1: Dan had a really rough day at work today. Sentence2: Dan went home and started cooking a steak. Sentence3: However, Dan accidentally burned the steak. Sentence4: Dan threw away the steak, and got dressed. Sentence5: Dan decided he would go to a local restaurant to eat dinner.
Output: Dan