Put 5 balls of each of the five colors of red, green, yellow, blue, and white into a box. At least how many balls are taken to ensure that two balls of the same color are taken.
把红、绿、黄、蓝、白五种颜色的球各5个放到一个箱子里．至少取多少个、个球，可以保证取到两个颜色相同的球．
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<result>6</result>