<|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
 In a class of 52 students, each student is assigned a random number. A systematic sampling method is used to select a sample of 4 students. It is known that students numbered 7, 33, and 46 are in the sample. What is the number of the fourth student in the sample? 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
20
In a class of 52 students, each student is assigned a random number. A systematic sampling method is used to select a sample of 4 students. It is known that students numbered 7, 33, and 46 are in the sample. What is the number of the fourth student in the sample?
test