using System;

​

class Program

{

    static void Main(string[] args)

    {        

        var auth = new Authentificator();    

        var client1 = new Client("Anna", "123456-12356");

        var acc1 = new Account("LV12345");

        var acc2 = new Account("EE23456");

        var acc3 = new Account("LT34567");

        if(auth.CheckPassword("abc123"))

        {

            client1.ChangeName("Elza");

        }

        else

        {

            Console.WriteLine("Authentification failed, password is incorrect!");

        }

        Console.WriteLine(client1.Introduce("Hey"));

    }

}

​

class Account

{

    private string _accountNumber;

    public string AccountNumber 

    {

        get {return _accountNumber;}

        private set 

        {

            if(value.Length == 7)

            {

                _accountNumber = value;    

            }

            else

            {

                throw new ArgumentException("Error: account number must contain 7 symbols!");

            }

        }    

    }

    public Account(string accountNumber)

    {

        try

        {

            AccountNumber = accountNumber;

        }

        catch(ArgumentException ex)

        {

            Console.WriteLine(ex.Message);

        }    

    }        

}

​

class Client

{

    private string _name;

    private string _ssn;

    public string Name 

    {

        get {return _name;}        

        private set

        {

            if(value != null && value.Length >= 2)

            {

                _name = value;

            }

            else

            {

                throw new ArgumentException("Name can not be null or less than 2 symbols!");

            }    

        }    

    }

    public string SSN 

    {

        get {return _ssn;}        

        private set

        {

            if(value.Length == 12)

            {

                _ssn = value;

            }

            else

            {

                throw new ArgumentException("SSN must contain 12 symbols!");

            }    

        }    

    }

    public Client(string name, string ssn)

    {

        try

        {

            Name = name;

            SSN = ssn;

        }

        catch(ArgumentException ex)

        {

            Console.WriteLine(ex.Message);

        }

    }

    public void ChangeName(string newName)

    {

        //Autherntificate first    

        Name = newName;        

    }

    public string Introduce(string greeting)

    {

        return $"{greeting}, my name is {Name} and my SSN is {SSN}";

    }

}

​

class Authentificator

{

    private string _correctPassword = "abc123";

    public bool CheckPassword(string password)

    {

        if(password == _correctPassword)

        {

            return true;

        }

        else

        {

            return false;

        }

    }    

}