You will be given a definition of a task first, then some input of the task.
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: Johnny was sixteen years old. Sentence2: He wanted nothing more than to pass his driving test. Sentence3: So Johnny's mother bought him book to help him study for the test. Sentence4: Unfortunately, Johnny never took the time to read it. Sentence5: When he finally took the test, Johnny failed.
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Johnny, Mother