There are 70 balls in the container, including 20 red balls, 20 green balls, 20 yellow balls, and the rest are black and white balls. The balls are of different colors. When touching the balls in the dark, it is necessary to ensure a certain color. There are no less than 10 balls, and the minimum number of balls must be drawn.
在容器中放有70个球，其中20个红色球，20个绿色球，20个黄色球，其余的黑色及白色球，球彼此颜色不同，在黑暗中摸球，要保证某一种颜色的球不少于10个，必须最少要摸出多少个球．
<gadget id="calculator">9 * 3</gadget>
<output>27</output>

<gadget id="calculator">70 - 20 - 20 - 20</gadget>
<output>10</output>

<gadget id="calculator">27 + 10 + 1</gadget>
<output>38</output>

<result>38</result>