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: My grandpa always sends me packets of newspapers in the mail. Sentence2: They often contain weekly comic strips and other fun tidbits. Sentence3: As he is over ninety years old, I am impressed by his agency. Sentence4: I always call him to thank him for the packets. Sentence5: When I'm older, I will never forget his kindness and generosity.
I (myself), Grandpa