There are 10 red, white, and black balls in each color, and they are mixed in a black cloth bag. The minimum number of balls that can be drawn out can ensure that there are 2 small balls of different colors.
有红、白、黑三种颜色的小球各10个，混放在一个黑色的布袋中，最少摸出多少个，才能保证有2个不同颜色的小球．
<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<result>11</result>