There are 4, 7, and 8 red, yellow, and black balls in a pocket respectively. In order to make 6 of the balls taken out be of the same color, at least how many small balls must be taken.
一个口袋里分别有红、黄、黑球4，7，8个，为使取出的球中有6个同色，则至少要取小球多少个．
<gadget id="calculator">4 + 5 + 5 + 1</gadget>
<output>15</output>

<result>15</result>