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.

Ex Input:
Sentence1: I used to deliver fliers everyday in the hot sun. Sentence2: My water bottle always ended up really hot. Sentence3: When I put ice in it, the ice melted. Sentence4: I decided to buy a special thermos that kept the cold in. Sentence5: Now I always had cold water when I was in the hot sun.

Ex Output:
I (myself)

Ex Input:
Sentence1: The man turned on the light. Sentence2: A mouse got startled. Sentence3: The mouse ran across the living room. Sentence4: The man got startled. Sentence5: The man hid in his room.

Ex Output:
The man, A mouse

Ex Input:
Sentence1: Sally went to friend's house after work. Sentence2: She brought a puppy with her that someone had left at her work. Sentence3: She told her friend Dan he should take the adorable puppy. Sentence4: After 1 hour with the cute puppy he couldn't resist. Sentence5: The puppy has been in Dan's life for 11 Year's now.

Ex Output:
Dan, Puppy, Sally, Friend