There are 8 red balls and 8 yellow balls in the box. How many balls can be drawn at most to ensure that there are two balls of different colors?
盒子里有红球和黄球各8个，最多摸出几个球，才能保证有两种颜色不相同的球？
<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<result>9</result>