There are 12 bags of salt, 11 bags of the same quality, one bag is not sure whether it is light or heavy, and the balance was used to find defective products at least several times.
有12袋盐，11袋质量相同，有一袋不知是轻还是重，用天平至少几次找到次品．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>