How many ways are there to put 4 distinguishable balls into 2 distinguishable boxes?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
How many ways are there to put 4 distinguishable balls into 2 distinguishable boxes?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
16
How many ways are there to put 4 distinguishable balls into 2 distinguishable boxes?
train