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: Alex was at the lake with his family. Sentence2: Some of the people were out on a boat. Sentence3: Suddenly an intense storm came rolling in. Sentence4: Everyone was worried about the people in the boat. Sentence5: Luckily, they had stopped on a beach and kept themselves safe.
Example Output: Some of the people, His family, Alex

Example Input: Sentence1: Bret went mountain climbing in Alaska. Sentence2: He was near the summit of the mountain when a storm struck. Sentence3: Bret had to build a snow cave to keep warm. Sentence4: Bret survived the storm that lasted two days. Sentence5: Bret was glad that he knew mountain survival techniques.
Example Output: Bret

Example Input: Sentence1: Maddie really wanted a puppy. Sentence2: Her mom told her if she gets all good grades, she could get one. Sentence3: She worked really hard for three months on her school work. Sentence4: When report cards came out, she had earned all a's and b's! Sentence5: Maddie's mom took her to get her puppy as her reward.
Example Output:
Maddie, A puppy, Her mom