<|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 school's emergency telephone tree operates as follows: The principal calls two students. In the first level, there is only the principal. In the second level, two students are contacted. For each subsequent level, each student contacts two new students who have not yet been contacted. This process continues with each student from the previous level contacting two new students. After the 8th level, how many students in total have been contacted? 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
254
A school's emergency telephone tree operates as follows: The principal calls two students. In the first level, there is only the principal. In the second level, two students are contacted. For each subsequent level, each student contacts two new students who have not yet been contacted. This process continues with each student from the previous level contacting two new students. After the 8th level, how many students in total have been contacted?
test