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: John was at home thinking about what to eat for dinner. Sentence2: He went to the fridge and looked inside. Sentence3: He saw that he had some fish. Sentence4: John cooked the fish in a frying pan. Sentence5: He ate the fish for dinner.
Example Output: John

Example Input: Sentence1: Waiting for the next train to pull up, Harry was nervous. Sentence2: He was only a few hours away from his big interview. Sentence3: Spending the last three months sending out resumes, this was it. Sentence4: Boarding the train, he noticed something strange about the inside. Sentence5: He had hopped on the wrong color train, and would be late.
Example Output: Harry

Example Input: Sentence1: Ben was playing game on his computer at home. Sentence2: His phone rang. Sentence3: He picked up the call from his mom. Sentence4: Her car was broken. Sentence5: He had to go to pick her up.
Example Output:
Ben, Mom