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.

Example Input: Sentence1: Sam wanted to learn how to read. Sentence2: He thought his friends would mock his illiteracy. Sentence3: But when they found out, they were all very kind. Sentence4: They even volunteered to teach him his letters. Sentence5: After months of studying, Sam became a great reader!
Example Output: His friends, Sam

Example Input: Sentence1: Anna loved pandas. Sentence2: Her zoo was having a panda exhibit. Sentence3: She was so excited! Sentence4: She went the first day the exhibit opened. Sentence5: She had such a wonderful time!
Example Output: Anna, Zoo

Example 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.
Example Output:
Beth, Santa claus