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: Lee was getting older. Sentence2: He noticed that he was having a lot of aches and pains. Sentence3: He hated this about getting older. Sentence4: He talked to his doctor about what to do. Sentence5: He started taking much better care of himself!
Output:
Lee, Doctor