Definition: 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.
Input: Sentence1: Brian took out his pocket knife and started to whittle. Sentence2: He made a snake that coiled around the branch he was whittling. Sentence3: A passerby was amazed at his talent and offered to purchase it. Sentence4: Brian asked for 10 dollars. Sentence5: The man gave him 20 dollars and told him to keep up the good work.
Output:
Brian, A passerby