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: Alex had a young son. Sentence2: The boy was three years old. Sentence3: He still wasn't speaking. Sentence4: Alex told the doctor about his speech issue. Sentence5: Alex's son started to see a speech therapist.

Output: Speech therapist, Alex, Young son, Doctor

Input: Consider Input: Sentence1: Randy was out jogging one morning. Sentence2: Then suddenly, the world began to look different. Sentence3: He realized he had lost a contact lens. Sentence4: He went back to check and see if he could find it. Sentence5: Sadly, though, Randy's lens was gone for good.

Output: Randy

Input: Consider Input: Sentence1: Chris went to an art gallery. Sentence2: He enjoyed all of the unique sculptures on display. Sentence3: He particularly enjoyed one piece. Sentence4: He saw a woman admiring the same piece. Sentence5: They got to chatting and became good friends.
Output: Chris, A woman