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: Johnny wanted a toy train for Christmas. Sentence2: He wrote a letter to Santa Claus and put it in the mailbox. Sentence3: Every day, he waited for a reply. Sentence4: Finally Christmas came, and Johnny rushed to look under the tree. Sentence5: Under the tree was a new train with a bow around it.
Output:
Santa claus, Johnny