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: John wanted to learn how to play the violin. Sentence2: He went to the music store to buy one. Sentence3: He selected a cheap model that he thought would do for a beginner. Sentence4: He started practicing and two strings broke right away. Sentence5: John went back to the store and bought a better violin.
Output:
John