<|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
 A child is making a 5-level pyramid by stacking some blocks. In the first row, he has 9 blocks. For the next rows, he has a certain pattern of blocks compared to its bottom row. He used 25 blocks in all. What is the pattern of blocks in each row compared to its bottom row? 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
2
A child is making a 5-level pyramid by stacking some blocks. In the first row, he has 9 blocks. For the next rows, he has a certain pattern of blocks compared to its bottom row. He used 25 blocks in all. What is the pattern of blocks in each row compared to its bottom row?
test