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: Casey was a secretary at a leasing office. Sentence2: There was a new hire, Savannah, whom Casey quickly became friends with Sentence3: Until the day Casey was running about one hour late to work. Sentence4: Savannah called the boss to tell on Casey. Sentence5: Casey and Savannah are not friends anymore.

Ex Output:
Casey, Savannah, Boss

Ex Input:
Sentence1: John did not know how to roller skate. Sentence2: His friend said that he would teach him. Sentence3: They spent all day practicing skating. Sentence4: John kept trying and got very good. Sentence5: Now he roller skates all over the neighborhood.

Ex Output:
John, Friend

Ex Input:
Sentence1: Joel liked being a bully. Sentence2: He was riding his bike when he saw Brandon from class. Sentence3: Brandon rode his bike up to Joel. Sentence4: Joel pushed Brandon off his bike and threw one leg over. Sentence5: As Joel tried riding away on both bikes he immediately fell over.

Ex Output:
Joel, Bike, Brandon