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.
Q: Sentence1: Jason watched the squirrel. Sentence2: Mark prepared the bate, a robotic squirrel tail. Sentence3: Next, Mark turned on the Squirrel tail and it bated. Sentence4: The bait was convincing and the squirrel reacted. Sentence5: The students determined squirrels communicate with their tails.
A:
Students, Jason, Squirrel, Mark