using System;

public class Program

{

    public static void Main()

    {

        Console.Write("請輸入使用者名稱");

        string username,password;

        username = Console.ReadLine();

        if ( username=="馬壯")

        {

        Console.WriteLine(username+"您好");

        Console.Write("請輸入密碼");

        password = Console.ReadLine();

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

         (password=="EGG566"))

        {

            Console.WriteLine("歡迎進入本系統");

        }

                    else

        {

            Console.WriteLine("密碼錯誤");

        {

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

        }

        }

        }

            else if (username=="徐強")

        {

        Console.WriteLine(username+"您好");

        Console.Write("請輸入密碼");

        password = Console.ReadLine();

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

         (password=="DOG123"))

        {

            Console.WriteLine("歡迎進入本系統");

        }

        }

        else

        {

            Console.WriteLine("密碼錯誤");

        {

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

        }

        }

    }

}

​