You will be given a definition of a task first, then some input of the task.
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: Mark loves to do puzzles Sentence2: He dedicates a lot of time to his hobby. Sentence3: He purchased a puzzle from a new company on Amazon. Sentence4: When the puzzle arrived, it was the best quality he had ever seen. Sentence5: He is so excited to do his new puzzle.
Output:
Mark