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: Sasha wanted a unicorn for Christmas. Sentence2: She had a pet horse in the stable. Sentence3: Sasha wanted one with a pretty horn on its head. Sentence4: She begged her mom all day before Christmas. Sentence5: Sasha woke up to her horse having a horn taped to its temple.
Sasha