Instructions: 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.
Input: Sentence1: An old man walked through a large park in the city. Sentence2: He began to feel tired so he looked for a bench. Sentence3: Nearby was a bench with some young people sitting on it. Sentence4: The old man was too bashful to ask for them to get up. Sentence5: The young noticed his suffering and stood up anyway.
Output:
Old man, Young people