There are stamp collectors from 12 different countries who want to exchange the latest stamps issued by each country by mail, so that everyone has stamps from 12 countries. Please find an exchange method that minimizes the number of communications, at least how many times.
有12个不同国家的集邮爱好者，想通过邮寄相互交换各国最新发行的邮票，使得每人都有12个国家的邮票．请找出一个使通信次数最少的交换方法，最少多少次．
<gadget id="calculator">11 + 11</gadget>
<output>22</output>

<result>22</result>