A brick path 1 meter wide is laid around a circular flower bed with a radius of 4 meters. What is the area of the brick path in square meters?
在一个半径是4米的圆形花坛四周铺一条1米宽的砖路，砖路的面积是多少平方米．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

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

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<gadget id="calculator">78.5 - 50.24</gadget>
<output>28.26</output>

<result>28.26</result>