What is the difference between the sum of the first 2003 even counting numbers and the sum of the first 2003 odd counting numbers?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the difference between the sum of the first 2003 even counting numbers and the sum of the first 2003 odd counting numbers?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
2003
What is the difference between the sum of the first 2003 even counting numbers and the sum of the first 2003 odd counting numbers?
train