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.
Q: Sentence1: Tim was visiting his grandparents. Sentence2: They didn't have wifi or fast internet. Sentence3: Their connection was still using dial up. Sentence4: Tim tried to use the internet but it was just too slow. Sentence5: He decided to just use his smart phone instead.
A:
Tim, Grandparents