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: Casey decided to bake a cake. Sentence2: She thought she bought all the ingredients. Sentence3: However, when she got home she could not find the icing. Sentence4: Casey had to go back to the store. Sentence5: Her cake was finally complete.
Casey