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: 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.
Example Output: John, Friend

Example Input: Sentence1: Every Saturday night my friends go bowling. Sentence2: Last week they invited me. Sentence3: I was so excited to go bowling with them. Sentence4: When we went bowling I did not do very well. Sentence5: Even though I didn't bowl well I had a lot of fun with my friends.
Example Output: I (myself), Friends

Example Input: Sentence1: Charles' father told him it was important to shine his shoes. Sentence2: Charles didn't see why, but he always kept his shoes shined. Sentence3: One afternoon, Charles interviewed for a management position. Sentence4: Charles was hired, but his boss said competition was close. Sentence5: He told Charles he was hired because the boss liked his shined shoes.
Example Output:
Charles, Father, Boss