The class leader should communicate a notice to the other 63 students in the class by phone. The class monitor first dials a phone number of a classmate, and then he and the classmate who has received the notice inform the unknown classmate at the same time.
班长要将一个通知用电话方式传达给班内其他63名同学．班长他先拨通一位同学的电话，然后他和已接到通知的同学同时再向班内未知的同学传达，当全班同学都接到通知时，班长至少要拨多少个电话．
<result>6</result>