There are 5 black balls, 8 white balls, 9 red balls, and 2 blue balls in a pocket. How many balls must be taken out at a time to ensure that there is at least one red ball.
一个口袋里有5个黑球，8个白球，9个红球，2个蓝球，一次至少取出多少个球才能保证至少有一个红球．
<gadget id="calculator">5 + 8 + 2 + 1</gadget>
<output>16</output>

<result>16</result>