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: Mary was learning to play her piano but not getting better. Sentence2: She talked to her teacher who explained that practice makes perfect. Sentence3: The teacher went over multiple lessons and helped Mary out. Sentence4: Mary went home and began playing but still had trouble. Sentence5: She smashed the piano keys with her hands and broke a finger.
Mary, Teacher