A snail climbed up a 12-meter-deep well from the bottom of the well, climbed 6 meters from morning to evening every day, and slid down 4 meters at night. Like this, starting from a certain morning, how many days did I climb out of the well.
一只蜗牛从井底沿着12米深的水井往上爬，每天从清晨到傍晚向爬6米，夜间又滑下来4米．像这样从某天清晨开始，第多少天爬出水井．
<gadget id="calculator">12 - 6</gadget>
<output>6</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>