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: Tina had sampled her mom's wine last night. Sentence2: Her mom had caught her and grounded her. Sentence3: But the next morning, Tina woke with a terrible hangover. Sentence4: She thought that was a far worse punishment than the grounding. Sentence5: Tina vowed never to drink alcohol again!
Example Output: Tina, Her mom

Example Input: Sentence1: Isaac was prone to bouts of depression. Sentence2: He never made many friends, and was usually found by himself. Sentence3: He imagined that no one would miss him and began to cry. Sentence4: His mother heard his sobbing and came to find out what was wrong. Sentence5: She encouraged him that she would miss him if he disappeared.
Example Output: Isaac, Friends, Mother

Example Input: Sentence1: Justin had a crush on Kate from the moment he saw her at school. Sentence2: Kate always smiled and said hello, but Justin could only blush. Sentence3: At the school dance, Justin saw Kate sitting quietly by herself. Sentence4: Summoning every bit of his courage, Justin asked her to dance. Sentence5: Kate said yes.
Example Output:
Justin, Kate