<|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
 On graph paper, a $12 \times 12$ square is drawn. What is the minimum number of its cells that need to be shaded so that a figure of the type shown in Figure 10 cannot be placed in the unshaded area? 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
72
On graph paper, a $12 \times 12$ square is drawn. What is the minimum number of its cells that need to be shaded so that a figure of the type shown in Figure 10 cannot be placed in the unshaded area?
test