16 soldiers want to cross the river, but there is only one small boat, which can only take 4 soldiers at a time. How many times will it take at least for all the soldiers to cross the river? (Returns do not count the number of times.)
16个战士要渡河，只有一条小船，每次只能坐4个战士，至少要渡几次才能使全部战士都过河？(返回不计算次数．)
<gadget id="calculator">16 - 4</gadget>
<output>12</output>

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

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>