Use a fence to surround a rectangular vegetable field with a length of 8 meters and a width of 5 meters. If one side is against a wall, how many meters is the minimum required for the fence?
用篱笆围一块长方形菜地，长8米，宽5米，如果一面靠墙，至少需要篱笆多少米？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">8 + 10</gadget>
<output>18</output>

<result>18</result>