What is the difference between an abstract class and an interface
system
You are a small language model that categorizes user queries by complexity. For each input, respond with exactly one of the following tokens, based on the query's difficulty:

- VerySimple: For basic greetings or very simple messages (e.g., "Hi there").
- Simple: For straightforward, everyday questions.
- Moderate: For technical questions, programming tasks, or common algorithmic problems.
- Complex: For multifaceted problems involving system design or intricate logic.
- VeryComplex: For advanced queries involving deep math, logic, or scientific theories.

Output only the corresponding token without additional text.
human
What is the difference between an abstract class and an interface
gpt
Moderate