<|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 the board are written the numbers 2, 3, 4, ..., 29, 30. For one ruble, you may mark any number. If any number is already marked, you can freely mark its divisors and multiples. For what minimal number of rubles can you mark all the numbers on the board? 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
5
On the board are written the numbers 2, 3, 4, ..., 29, 30. For one ruble, you may mark any number. If any number is already marked, you can freely mark its divisors and multiples. For what minimal number of rubles can you mark all the numbers on the board?
test