编辑代码

using System;  
  
class Program  
{  
    static void Main()  
    {  
        string username = Console.ReadLine();  
        string password = Console.ReadLine();  
  
        if (username == "admin" && password == "88888")  
        {  
            Console.WriteLine("正确");  
        }  
        else if (username != "admin")  
        {  
            Console.WriteLine("用户名不存在");  
        }  
        else  
        {  
            Console.WriteLine("密码错误");  
        }  
    }  
}