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: Paul had a problem with drugs. Sentence2: His Father was very concerned for him. Sentence3: He put him in a rehab center to get help. Sentence4: Paul stayed there for sixty days. Sentence5: He learned how bad drugs really were and never did them again.

Ex Output:
Paul, Father

Ex Input:
Sentence1: Kirk went to the bank to deposit a check. Sentence2: He was very late for work but stood in line anyway. Sentence3: The line moved very slowly. Sentence4: To pass the time he took a lollipop in one of the bowls. Sentence5: He had finished the lollipop when it was finally his turn.

Ex Output:
Kirk

Ex Input:
Sentence1: Eric had a new sled that he couldn't wait to try out. Sentence2: Only there wasn't any snow yet. Sentence3: Finally on Saturday morning he woke up and it had snowed. Sentence4: He called his friend John to meet him on the hill by the school. Sentence5: They took turns riding down the hill on Eric's new sled.

Ex Output:
John, Eric