There are 10 red and 10 white chopsticks, at least how many chopsticks must be taken to ensure that there is a pair of the same color.
有红色、白色的筷子各10支，至少要拿多少支筷子，才能保证有一双是同色的．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>