There are some balls in a bag, these balls are only different in color. Among them, there are 10 red balls, 9 white balls, 8 yellow balls, and 2 blue balls. Someone takes out some of them with his eyes closed. Ask him how many balls he must take at least to ensure that at least 4 balls have the same color.
一个袋里有一些球，这些球仅只有颜色不同．其中红球10个，白球9个，黄球8个，蓝球2个，某人闭着眼睛从中取出若干个．问他至少要取多少个球，方能保证至少有4个球颜色相同．
<gadget id="calculator">2 + 3 + 3 + 3 + 1</gadget>
<output>12</output>

<result>12</result>