There are 37 students who want to cross the river by boat. There is only one empty boat by the river which can carry 5 people.
有37名同学要坐船过河，河边只有一条能载5人的空船，他们全部渡过河去，最少要渡多少次．
<gadget id="calculator">37 - 5</gadget>
<output>32</output>

<gadget id="calculator">32 / 4</gadget>
<output>8</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<result>9</result>