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.

Example Input: Sentence1: Last year Paul was about an inch too short for the big roller coaster. Sentence2: He was confident when he walked up to the measuring stick. Sentence3: Sure enough, he had grown well over an inch. Sentence4: He proudly got on the roller coaster. Sentence5: It was as much fun as he expected it to be!
Example Output: Paul

Example Input: Sentence1: Dean decided he was going to prank his principle. Sentence2: He took a carton of eggs from his fridge and headed out. Sentence3: He arrived at his principal's house a little after midnight. Sentence4: After throwing two eggs his principle came outside. Sentence5: He was forced to clean up the mess and serve detention for a month.
Example Output: Dean, Principal

Example Input: Sentence1: My mother and I were hit by lightning. Sentence2: We both had just gotten into the car. Sentence3: The entire car shook for a few seconds and all the window lit up. Sentence4: We both couldn't believe it and looked at each other. Sentence5: Then we drove away.
Example Output:
I (myself), My mother