There are 4 red and 4 yellow balls in an opaque bag, at least how many balls must be drawn to ensure that 2 balls of the same color are touched.
在一个不透明的袋子中装有红、黄两种颜色的球各4个，至少要摸出多少个球才能保证摸到两个同颜色的球．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>