There are 10 chalks of red, yellow, and blue colors, and at least 3 chalks of any color can be obtained when at least how many chalks are taken at one time (do not look at the color of the chalks when taking them).
有红、黄、蓝三种颜色粉笔各10支，在一次至少拿多少支时(拿时不许看粉笔颜色)，才能保证得到任意一种颜色的粉笔至少有3支．
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">20 + 3</gadget>
<output>23</output>

<result>23</result>