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: Consider Input: Sentence1: Greta had noticed her son was having trouble focusing in school. Sentence2: Greta took her son to the doctor. Sentence3: The doctor diagnosed the boy with ADHD. Sentence4: The doctor prescribed medicine for him. Sentence5: Greta's son now focuses much better in class.

Output: Greta, Greta's son, The doctor

Input: Consider Input: Sentence1: Sheena fell asleep last night with gum in her mouth. Sentence2: The gum must have fallen out while she was sleeping. Sentence3: When she woke up this morning she had the gum stuck in her hair. Sentence4: Her mom had to cut the gum out of hair. Sentence5: Sheena's hair looks funny now.

Output: Sheena, Her mom

Input: Consider Input: Sentence1: Ronnie was headed to a city for a baseball game. Sentence2: His car had been running hot. Sentence3: He decides to pull over because he smelt smoke. Sentence4: He pops his hood and see's his engine almost on fire. Sentence5: He waits for help on the side of the road.
Output: Ronnie