Given the task definition and input, reply with output. 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.

Sentence1: Charles was 10-years-old when his uncle took him skiing. Sentence2: He suited up, buckled his skis, but the guys skied off! Sentence3: Charles began sliding backwards down a slope. Sentence4: He skied faster and faster, knocking people down in his path. Sentence5: A guard stopped Charles and then said he must be a professional.
His uncle, Guard, Charles, Guys, People