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: Sam was about to close down the store. Sentence2: At the last minute some customers went up to the door. Sentence3: They begged Sam to let them get one thing real quick. Sentence4: Sam reluctantly agreed to it. Sentence5: Luckily the ran in and out faster than expected.
A:
Some customers, Sam