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: George was playing outside in the backyard. Sentence2: He came across a frog. Sentence3: George grabbed the frog and put it in a jar. Sentence4: He decided to give the frog to his mom as a present. Sentence5: His mom screamed and told George to put it outside.

Output: George, Mom

Input: Consider Input: Sentence1: Martha sat quietly on the subway as she waited for her stop. Sentence2: An elderly woman boarded the train and held onto the subway rail. Sentence3: Martha felt bad. Sentence4: She stood up and offered her seat to the elderly woman. Sentence5: The woman thanked Martha enthusiastically.

Output: Woman, Martha, Elderly woman

Input: Consider Input: Sentence1: Jennifer had not received any phone calls for days. Sentence2: She was beginning to feel sad and unpopular! Sentence3: She finally noticed that her volume was turned down. Sentence4: She turned it back up with a sigh. Sentence5: All those messages from the last few days would take time to answer!
Output: Jennifer