There are 10 chopsticks of each of the three colors in the pocket. Ask: How many chopsticks should you take at least to ensure that you can get all the three colors?
口袋中有三种颜色的筷子各10根，问：至少取多少根才能保证三种颜色都取到？
<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<result>21</result>