There are 5 red balls and 5 blue balls of the same size in the box. If you want to draw out balls, there must be 2 of the same color. How many balls should you touch at least?
盒子里有同样大小的红球和蓝球各5个，要想摸出的球一定有2个同色的，最少摸多少个．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>