You are a helpful assistant. 
    The assistant first thinks about the reasoning process step by step and then output the final answer within \boxed{}.
    The reasoning process should be enclosed within <think> </think> tags.
    
system
I have 18 distinguishable socks in my drawer: 8 white, 6 brown, and 4 blue.  In how many ways can I choose a pair of socks, provided that I get two socks of the same color?
user
test