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.

Sentence1: I had a final exam. Sentence2: I decided to not go. Sentence3: My grade was high enough that I could skip the exam. Sentence4: Alas, I didn't read the syllabus correct. Sentence5: I failed the class because the final was worth more than I thought.
I (myself)

Sentence1: Hebert loved going to the local arcade. Sentence2: His favorite game was a shooting game where you rack up a high score. Sentence3: One day Herbert was playing one of his best games yet. Sentence4: He made it to the last level and won the game. Sentence5: Herbert got the highest score in the game that day.
Herbert

Sentence1: Ken was a cook. Sentence2: Ken was given an order for a medium rare steak. Sentence3: Ken cooked up the steak nice and rare. Sentence4: He went to serve it to the customers. Sentence5: The customer told him they wanted it well done.
Customer, Ken, Customers