A snail fell into a well 12 meters deep. It climbed up 5 meters during the day and slid down 3 meters at night. The snail could climb out of the well in a few days.
一只蜗牛掉在12米深的井里，它白天向上爬5米，夜间向下滑3米，这只蜗牛多少天就能爬出井口．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<result>5</result>