Detailed Instructions: 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.
Q: Sentence1: Sean turned twenty-one years old. Sentence2: He decided to start drinking beer. Sentence3: Over the years, Sean became an alcoholic. Sentence4: One day, he realized that the beer was killing him. Sentence5: Sean decided to quit drinking beer.
A:
Sean