There are some small balls of the same size and different colors in a cloth bag, including 10 red balls, 9 white balls, 8 yellow balls, and 2 blue balls. What is the minimum number of balls to be taken at a time to ensure that there are 4 balls of the same color? ．
一个布袋里有大小相同、颜色不同的一些小球，其中红的10个，白的9个，黄的8个，蓝的2个，一次最少取多少个球，才能保证有4个球颜色相同．
<gadget id="calculator">11 + 1</gadget>
<output>12</output>

<result>12</result>