Uncle Li’s family has a vegetable field, which is 18 meters long and 15 meters wide, and one side is against the wall. If the other three sides are surrounded by fences, what is the maximum length of the fence?
李大伯家有一块菜地，长18米，宽15米，一面靠墙，如果另外三面围上篱笆，最多用多少米长的篱笆？
<gadget id="calculator">18 + 18 + 15</gadget>
<output>51</output>

<result>51</result>