198*198-197*199．
198*198-197*199．
<gadget id="calculator">198 * 198</gadget>
<output>39_204</output>

<gadget id="calculator">197 * 199</gadget>
<output>39_203</output>

<gadget id="calculator">39_204 - 39_203</gadget>
<output>1</output>

<result>1</result>