using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("請輸入使用者名稱:");

        string username,password;

        username=Console.ReadLine();

    if(username=="馬壯")

    {

        Console.WriteLine(username+"你好");

        Console.Write("請輸入密碼:");

        password=Console.ReadLine();

        if((password=="egg566")||

           (password=="EGG566"))

        {

            Console.WriteLine("歡迎加入本系統");

        }   

        else

        {

            Console.WriteLine("密碼錯誤");

        }   

    }

        else if(username=="徐強")

        {

            Console.WriteLine(username+"你好");

        }

        else

        {

            Console.WriteLine("本系統不認識"+username);

        }

        Console.Write("請輸入密碼:");

        password=Console.ReadLine();

        if((password=="dog123")||

           (password=="DOG123")||

          (password=="Dog123"))

        {

            Console.WriteLine("歡迎加入本系統");

        }   

        else

        {

            Console.WriteLine("密碼錯誤");

        }   

    }       

    }

​