There are 4 table tennis balls of 2 colors, yellow and 4 white, in a paper box. If you want to find 2 balls of the same color, how many balls should you touch at least?
一个纸盒里放有黄、白2种颜色的乒乓球各4个，要想摸出的球一定有2个同颜色的，最少要摸多少个球．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>