using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("請輸入密碼");

        string pass=Console.ReadLine();

        string correct="abcd";

        while(pass!=correct)

        {

            string use=Console.ReadLine();

            if(use!=correct)

            {

                Console.WriteLine("錯誤");

            }

        }

        Console.WriteLine("密碼正確");

    }

}