Definition: 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: Matt began his exercise routine by stretching. Sentence2: He was excited already, but he was anxious when Mia joined him. Sentence3: She smiled and handed him a jump rope. Sentence4: Time for their weekly challenge, he thought, beginning to jump. Sentence5: He jumped fifty times before stopping.
Output:
Mia, Matt