There are 21 members in a sports team. The teacher wants to notify each team member as soon as possible. If the "one pass one" method is used to notify one person every minute, it will take at least how many minutes to notify everyone.
一个运动队共有21人，教师想尽快通知到每一个队员，如果采用"一传一"的方法用打电话的方式，每一分钟通知1人，最少花多少分钟就能通知到每个人．
<result>5</result>