Simplify the expression $a+1+a-2+a+3+a-4$.
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Simplify the expression $a+1+a-2+a+3+a-4$.
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
4a-2
Simplify the expression $a+1+a-2+a+3+a-4$.
train