A cuboid has sides whose sum is 20 centimeters, length 2 centimeters, width 1 centimeter, and height in centimeters.
一个长方体，它的棱长总和是20厘米，长是2厘米，宽是1厘米，高是多少厘米．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 - 2 - 1</gadget>
<output>2</output>

<result>2</result>