There are 9 glass balls of the same size in a box, among which there are 9 red ones, 8 white ones, 7 yellow ones, and 6 green ones. In order to ensure that there must be 8 glass balls of the same color.
在一个盒子里装有大小相同的玻璃球，其中红色的有9粒，白色的有8粒，黄色的有7粒，绿色的有6粒，如果不用眼睛看，那么从中至少摸出多少粒球才能保证一定有8粒颜色一样的玻璃球．
<gadget id="calculator">7 + 7 + 7 + 6 + 1</gadget>
<output>28</output>

<result>28</result>