There are 2 white balls and several red balls in the box, at least how many balls must be drawn at a time to ensure that there are red balls.
箱子里有2个白球和若干个红球，一次至少要摸出多少个球，才能保证有红球．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>