A conical container with a bottom radius of 4 cm and a height of 9 cm is filled with water and poured into a cylindrical container with a bottom area of 12.56 cm2 and a height of 20 cm. How many centimeters is the water surface from the container mouth?
一个圆锥形容器，底面半径是4厘米，高9厘米，将它装满水后，倒入底面积是12.56平方厘米、高20厘米的圆柱形容器中，水面离容器口还差多少厘米？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">(1/3) * 3.14 * 16 * 9</gadget>
<output>150.72</output>

<gadget id="calculator">150.72 / 12.56</gadget>
<output>12</output>

<gadget id="calculator">20 - 12</gadget>
<output>8</output>

<result>8</result>