Put 10 balls of red, yellow, blue, and white into a bag, and take at least how many balls to ensure that you get two balls of the same color.
把红、黄、蓝、白四种颜色的球各10个放到一个袋子里，至少取多少个球，才能保证取到两个颜色相同的球．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>