using System;

public class PhoneNumber
{
    public PhoneNumber(string phoneNumber)
    {
    }

    public string Number
    {
        get
        {
            throw new NotImplementedException("You need to implement this function.");
        }
    }

    public string AreaCode
    {
        get
        {
            throw new NotImplementedException("You need to implement this function.");
        }
    }
}