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 went into the forest to find a tree for wood. Sentence2: He selected a tall oak tree with big branches. Sentence3: John swung his ax at the trunk until it fell. Sentence4: The tree came down with a big crash. Sentence5: John sat on his tree and rested.
Output:
John