box contains 10 black and white chess pieces each, and at least how many pieces can be drawn from it to ensure that there are 3 pieces of the same color.
一个盒子里装有黑白两种颜色的棋子各10颗，从中至少摸出多少颗才能保证有3颗颜色相同．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>