There are 15 black balls, 13 white balls and 10 red balls in the pocket, at least how many balls can be drawn from it to ensure that there must be white balls among them.
口袋中有15个黑球，13个白球和10个红球，至少从中摸出多少个球，才能保证其中一定有白球．
<gadget id="calculator">15 + 10 + 1</gadget>
<output>26</output>

<result>26</result>