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: Beth sent a letter to Santa Claus. Sentence2: She received a letter back in the mail. Sentence3: Beth did not think that it sounded like the real Santa. Sentence4: She sent another letter calling that Santa a fake. Sentence5: She did not receive another letter back in the mail.
Output:
Beth, Santa claus