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: She had been waking up every morning sick. Sentence2: She knew this was not normal. Sentence3: She went to the doctor to get things checked out. Sentence4: The results were confirmed. Sentence5: She was pregnant.
Example Output: Doctor

Example Input: Sentence1: Paul had a problem with drugs. Sentence2: His Father was very concerned for him. Sentence3: He put him in a rehab center to get help. Sentence4: Paul stayed there for sixty days. Sentence5: He learned how bad drugs really were and never did them again.
Example Output: Paul, Father

Example Input: Sentence1: When I was a kid, my mom and dad divorced. Sentence2: After the divorce, my mom wouldn't let me see my dad. Sentence3: When I got older, my dad contacted me. Sentence4: He wanted to have lunch and talk. Sentence5: I showed up, but he did not show up that day.
Example Output:
Dad, I (myself), Mom, Kid