There are 6 red and 6 white balls, put them in a cloth bag after mixing, and touch at least how many balls at a time to ensure that there are two balls of the same color.
有红和白两种颜色的球各6个，混合后放在一个布袋里，一次至少摸多少个球，才能保证有两个球是同种颜色的．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>