There are several red balls, yellow balls, and blue balls in the box, and at least how many balls are taken from them to ensure that there are 4 balls of the same color.
盒子中有红球、黄球、蓝球若干个，从中至少取多少个球，才能保证有4个球同色．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<result>10</result>