There are 4 red, yellow, and blue balls in the bag, at least how many balls are randomly taken out to ensure that there are 2 balls of a certain color.
袋子中有红、黄、蓝球各4个，至少任意拿出多少个球，才能保证某种颜色的球有2个．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>