Uncle Li built a rectangular rabbit house with a length of 15 meters and a width of 3 meters at the corner of the yard. How many meters should the wall be repaired at least?
李叔叔在院子的墙角修了一个长15米，宽3米的长方形兔舍，至少需要修围墙多少米？
<gadget id="calculator">15 + 3</gadget>
<output>18</output>

<result>18</result>