There are 9 black socks and 9 white socks in a black box. At least how many socks must be drawn from the box to ensure that there are 3 pairs of the same color.
在一个黑箱里方有黑色和白色的袜子各9只，至少要从中摸出多少只才能保证有3双同色．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">1 + 6</gadget>
<output>7</output>

<result>7</result>