There are 6 basketballs and 6 yellow balls with exactly the same shape and size in the cloth bag, at least how many balls can be drawn to ensure that there are two balls of the same color.
布袋里有形状大小完全一样的篮球和黄球各6个，至少摸出多少个才能保证有两种颜色相同的球．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>