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: Nick, Bob, Sam, and Don went to a rock show in Philadelphia last week. Sentence2: They found their seats with help from an usher. Sentence3: The group then searched for the merchandise booth. Sentence4: Three of them bought vinyl records. Sentence5: They returned to their seats to watch the rest of the show.
Don, Sam, Three of them, Nick, Usher, Bob