There is a circular flower bed in the school with a diameter of 4 meters. A 1m path is paved around it. What is the area of the path in square meters?
学校有个圆形花坛的直径是4米，在它的周边围铺一条1m的小路，这条小路的面积是多少平方米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<gadget id="calculator">9 - 4</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<result>15.7</result>