The snail crawls from a dry well net, climbs up 110 cm during the day, and slides down 40 cm at night. If it is to climb to the mouth of the well in the daytime on the fifth day, how deep should the well be at least?
蜗牛从一个枯井网上爬，白天向上爬110厘米，夜里向下滑40厘米，若要第五天的白天爬到井口，这口井至少深多少厘米．
<gadget id="calculator">110 - 40</gadget>
<output>70</output>

<gadget id="calculator">70 * 3</gadget>
<output>210</output>

<gadget id="calculator">210 + 110 + 1</gadget>
<output>321</output>

<result>321</result>