Uncle Zhang wants to surround a rectangular chicken coop with a length of 12 meters and a width of 8 meters against the wall. How many meters of fence does he need at least?
张大爷想靠墙围一个长是12米、宽是8米的长方形鸡舍，他至少需要多少米围栏？
<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">16 + 12</gadget>
<output>28</output>

<result>28</result>