How many floors does the elevator need to go through from the 1st floor to the 6th floor, and then back to the 1st floor?
电梯从1楼到6楼，再回到1楼，需要经过多少层．
<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<result>10</result>