<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 The school plans to hold special lectures for four subjects—Chinese, Mathematics, English, and Science Comprehensive—during the first, second, and third classes of Friday afternoon. Each subject occupies one class period, and there must be at least one subject per period. Given that Mathematics and Science Comprehensive cannot be arranged in the same period, calculate the total number of different arrangements. Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
24
The school plans to hold special lectures for four subjects—Chinese, Mathematics, English, and Science Comprehensive—during the first, second, and third classes of Friday afternoon. Each subject occupies one class period, and there must be at least one subject per period. Given that Mathematics and Science Comprehensive cannot be arranged in the same period, calculate the total number of different arrangements.
test