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: David was whistling in class. Sentence2: The teacher didn't know who was making the noise. Sentence3: She didn't know who to punish. Sentence4: One of the students told the teacher after class that it was David. Sentence5: The next time David whistled, the teacher blamed David.
Example Output: One of the students, Teacher, David

Example Input: Sentence1: Burt left his car windows down one sunny day in New Jersey. Sentence2: The weather changed and soon it started to downpour. Sentence3: Burt ran to his car and rolled up his windows during the storm. Sentence4: The inside was not very wet yet. Sentence5: Burt sighed in relief and vowed to never be so foolish again.
Example Output: Burt

Example Input: Sentence1: During winter break, I went to the mall with a few friends. Sentence2: We ate dinner and walked around the outlet stores. Sentence3: Before we left, we decided to go to the bathroom. Sentence4: Although it was hard to believe, I ran into other friends. Sentence5: We talked for a little bit and exchanged phone numbers.
Example Output:
I (myself), Other friends, Other friends