19 soldiers came to a river to cross the river, but there was only one boat by the river, and the boat could only take up to 4 people at a time (not including the boatman). Think about it, at least how many times can the boat transport all the soldiers across the river?
19个战士来到一条河边准备过河，可是河边只有一条船，小船一次最多只能坐4个，(不包括船夫)．想一想，小船至少几次才能将战士全部运过河？
<gadget id="calculator">19 - 4</gadget>
<output>15</output>

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

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<result>6</result>