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: Val's mom was furious with her. Sentence2: Val liked to her about being bullied. Sentence3: Val was in fact the bully. Sentence4: Her mother was embarrassed when the principal showed her the proof. Sentence5: Val was grounded for a month for being a bully, and telling lies.
Output:
Mom, Val, Principal