There are wooden balls of the same size but different colors in a bag, including 10 red balls, 9 white balls, 2 blue balls, and 8 yellow balls. How many balls should be taken at least once to ensure that 4 of them are balls of the same color?
一个布袋里有大小相同而颜色不同的木球，其中红球10个，白球9个，蓝球2个，黄球8个．一次至少取多少个球，才能保证其中4个是同色球多少
<gadget id="calculator">11 + 1</gadget>
<output>12</output>

<result>12</result>