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: Rakesh was 10-years-old and his parents owned a motel. Sentence2: They believed their son Rakesh should have money to buy things. Sentence3: Rakesh bought toys from the hobby store, but his friend didn't. Sentence4: Rakesh gave his friend, Charles, $75! Sentence5: But Charles showed his mother the cash and she made him return it.

Ex Output:
His parents, Motel, Rakesh, His mother

Ex Input:
Sentence1: Warren didn't like beets and told his mom repeatedly. Sentence2: But as she never listened, he had some on his plate for dinner. Sentence3: He tried to give them to his dog. Sentence4: The dog sniffed them and walked away. Sentence5: Warren refused to eat the beets as his dog didn't want them either.

Ex Output:
Dog, Mom, Warren

Ex Input:
Sentence1: Debbie worked at a coffee shop. Sentence2: Her favorite customer was a man named Stan. Sentence3: Stan tipped her fifty dollars one day. Sentence4: Debbie stopped Stan, thinking it was a mistake. Sentence5: Stan smiled and reassured her to keep the money.

Ex Output:
Stan, Debbie