There are 7 socks of red, yellow, and blue in a cloth bag, how many socks are taken out at a time, so as to ensure that there is at least one sock of each color.
一个布袋里装有红、黄、蓝三种颜色的袜子各7只，一次至少取出多少只，才能保证每种颜色的袜子至少有一只．
<gadget id="calculator">7 + 7 + 1</gadget>
<output>15</output>

<result>15</result>