There are 20 people crossing the river, and there are 5 people in the boat each time, how many times can they all cross the river at least?
有20个人过河，小船每次坐5个人，求至少几次才能全部过河？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>