Q: 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: John was very nervous about his upcoming flight. Sentence2: He couldn't sleep the whole night before the flight. Sentence3: In the morning, he threw up due to his anxiety. Sentence4: He took an anxiety pill to help him sleep before his flight. Sentence5: John had no problem with his flight after he took his pill.
A:
John