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.

Example input: Sentence1: My dog was bored. Sentence2: I was working all day so I couldn't spend time with him. Sentence3: When I finished work I decided to play with my dog. Sentence4: He was so happy to finally have some fun! Sentence5: Alas, he fell sick and died.
Example output: I (myself), Dog
Example explanation: There is only two characters in given story, i.e., I (myself) and dog.
Q: Sentence1: Mitch was trying to earn a few extra dollars over the summer. Sentence2: He offered to mow his neighbor's' yards. Sentence3: Four of his neighbors took him up on the offer. Sentence4: Mitch mowed their yards once a week. Sentence5: By the end of the summer, Mitch had saved up a couple hundred dollars.
A:
Neighbors, Mitch, Four neighbor