A gravel road with a width of 1 meter is laid on the periphery of a circular flower bed with a diameter of 4 meters. What is the area of the gravel road in square meters?
在一个直径是4米的圆形花坛的外围铺上一条宽1米的石子路．这石子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>