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: Yusuf was startled by a loud knocking at his door at a late hour. Sentence2: He wasn't expecting company, and grabbed his gun. Sentence3: A shivering woman greeted him when he opened the door. Sentence4: She had hit black ice and her car had slid off the road. Sentence5: Yusuf called a tow truck for her, and let her warm up in his house.

Output: Yusuf, Woman

Input: Consider Input: Sentence1: Steve was very nervous to ask Tina out on a date. Sentence2: Steve had liked Tina for months now, but they never really spoke. Sentence3: Steve got encouragement from his friends to ask her to hang out. Sentence4: Steve gathered courage and asked Tina to study together that night. Sentence5: Tina said yes and soon they started dating each other!

Output: Steve, Friends, Tina

Input: Consider Input: Sentence1: Charles was obsessed with crossword puzzles. Sentence2: Every morning, Charles would attempt the New York Times crossword. Sentence3: He loved the challenge of completing the daily crossword. Sentence4: There are days where Charles cannot complete the crossword puzzle. Sentence5: However, since Charles loves crosswords, he continues to attempt them.
Output: Charles