Calculation: 1+2-3-4+5+6-7-8+9+10-11-12+13+...+1994-1995-1996+1997=how much.
计算：1+2-3-4+5+6-7-8+9+10-11-12+13+…+1994-1995-1996+1997=多少．
<gadget id="calculator">(-4) * 499</gadget>
<output>-1_996</output>

<gadget id="calculator">(-1_996) + 1_997</gadget>
<output>1</output>

<result>1</result>