1+2-3+4-5+...-99+100=how much.
1+2-3+4-5+…-99+100=多少．
<gadget id="calculator">(-99) + 100</gadget>
<output>1</output>

<gadget id="calculator">1 * 49</gadget>
<output>49</output>

<gadget id="calculator">1 - 49</gadget>
<output>-48</output>

<gadget id="calculator">(-48) + 100</gadget>
<output>52</output>

<result>52</result>