The height of the tree is 5 feet, Xiao Ming climbs up 3 feet every minute, and then retreats 1 foot, how many minutes does it take Xiao Ming to climb to the top.
树高5尺，小明每分钟上爬3尺，再退回1尺，小明多少分钟爬到数尖．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<result>2</result>