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: I found out one of my coworkers was a good chess player. Sentence2: I met him at lunch to play a game. Sentence3: He beat me easily. Sentence4: He offered to give me chess lessons instead of playing. Sentence5: I learned a lot from him.
I (myself), My coworkers