What is the units digit of $19^{19}+99^{99}$?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the units digit of $19^{19}+99^{99}$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
8
What is the units digit of $19^{19}+99^{99}$?
train