company1-2

代码说明：

  公司有n个员工，编号1 ~ n。员工数量众多，需要你为他们编写一个管理系统。 　　员工上班时都要登录管理系统登记一个code，离开要从管理系统上注销，员工也可以随时更新自己的code。到了下班时间，所有员工都会自动注销。公司管理人员随时都可能想要知道有多少员工上班，以及任一员工登记的code。(The company has n employees, number 1 ~ n. There are so many employees that you need to write a management system for them. When employees go to work, login to the management system to register a code, leave to log off from the management system, employees can also update their code at any time. By the end of the day, all employees will automatically log out. Company managers may at any time want to know how many employees go to work, and the number of code registered by any employee.)