The winter vacation is coming soon, and Mr. Li discussed with the students of Class 61 the following question: If there is an urgent matter during the vacation and you need to call (each call takes 1 minute) to inform everyone, then how many minutes will it take Mr. Li to get it as soon as possible? Notify the 45 students in the class.
寒假快要到了，李老师与六1班的同学们讨论这样一个问题：如果假期中有急事需要打电话(每打一个电话需要1分钟时间)通知大家，那么，李老师至少要花多少分钟才能尽快通知全班的45名同学．
<result>6</result>