Put 5 red balls and 5 yellow balls in a wooden box. At least how many balls must be picked to ensure that there are two of the same color.
在一个木箱里放红球和黄球各5个，至少要抓出多少个才能保证颜色相同的有两个．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>