Calculation: 2003+2002-2001-2000+1999+1998-1997-1996+...+7+6-5-4+3+2-1.
计算：2003+2002-2001-2000+1999+1998-1997-1996+…+7+6-5-4+3+2-1．
<gadget id="calculator">2_002 - 2_001</gadget>
<output>1</output>

<gadget id="calculator">2_003 + 1</gadget>
<output>2_004</output>

<result>2_004</result>