A bag contains 80 red balls, 70 blue balls, 60 yellow balls, and 50 white balls. They are all the same in size and quality, and you are not allowed to look at them, but you are only allowed to touch them with your hands. To ensure that 10 pairs of balls of the same color are drawn, at least how many should be drawn.
袋子里装有红色球80只，蓝色球70只，黄色球60只，白色球50只．它们的大小与质量都一样，不许看只许用手摸取，要保证摸出10对同色球，至少应摸出多少只．
<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">5 + 18</gadget>
<output>23</output>

<result>23</result>