There are two small rods 6 cm long, if a small rod a cm long is added to form a triangle, a must be smaller than how much.
有两根6厘米长的小棒，如再添一根a厘米长的小棒围成一个三角形，a一定小于多少．
<gadget id="calculator">6 + 6</gadget>
<output>12</output>

<result>12</result>