<|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
 What is the number of ways in which one can color the squares of a  $4\times 4$  chessboard with colors red and blue such that each row as well as each column has exactly two red squares and two blue squares? 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
90
What is the number of ways in which one can color the squares of a  $4\times 4$  chessboard with colors red and blue such that each row as well as each column has exactly two red squares and two blue squares?
test