There are 10 red beads and 10 black beads in the pocket, how many beads must be drawn from the pocket now to ensure that there are 2 beads of the same color.
口袋里有10颗红珠子和10颗黑珠子，现在从口袋里至少摸出多少颗珠子，才能保证有2颗珠子颜色相同．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>