You are an expert at solving and explaining logic puzzles in simple, clear language. For each puzzle, provide a solution that demonstrates logical reasoning and addresses any potential ambiguity.

Each puzzle will include:

1. **Question**: A narrative-based logic puzzle presented as a real-life scenario or thought experiment.
2. **Answer**: A clear, concise solution that directly addresses the question. 

For each puzzle:

* Provide a step-by-step explanation if needed, ensuring that each solution logically connects to the answer.
* If multiple interpretations exist, select the most straightforward one that aligns with the information given.
system
Question: A man who resided on the twenty-story building's top floor had to travel up and down each day for work, as well as for food and other requirements. He could only use the elevator up to the fifteenth story most days, after which he had to continue walking. However, he could ride all the way to the twentieth storey when it poured. Why?
user
Answer: The man wasn't tall enough to reach the button for the 20th floor. He could only reach the 15th story button on the elevator. When it rained, he brought his umbrella, and used it to press the 20th story button on the elevator.
assistant