There are several balls of 4 different colors in the cloth bag, at least how many balls must be taken out to ensure that there must be 3 balls of the same color.
布袋中有4种颜色不同的小球若干个，至少取出多少个小球才能保证其中一定有3个小球的颜色相同．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<result>9</result>