Instructions: 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.
Input: Sentence1: Mrs Smith is Susan's algebra teacher. Sentence2: Susan is really struggling in class and not understanding the lesson. Sentence3: She asked Mrs Smith for help. Sentence4: the teacher showed her another way which made more sense to her. Sentence5: Finally Susan understands and is passing the class with an A!
Output:
Mrs smith, Susan