There are 10 balls of five colors in a box, at least how many balls can be drawn from it to ensure that there are 2 balls of the same color.
一个盒子里装有五种颜色的球各10个，从中至少摸出多少个才能保证有2个是相同颜色的．
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<result>6</result>