public class Contact
{
    public int ID;
    public string FirstName
    {
        get;
        set;
    }
    public string SecondName
    {
        get;
        set;
    }
    public string EMail
    {
        get;
        set;
    }
    public Contact()
        {
        this.ID=9999;
        }
    public Contact(int ID)
    {
        this.ID = ID;
    }
    public Contact(int ID, string FirstName, string SecondName)
    {
        this.ID = ID;
        this.FirstName = FirstName;
        this.SecondName = SecondName;
    }
    public Contact(int ID, string FirstName, string SecondName, string EMail)
    {
        this.ID = ID;
        this.FirstName = FirstName;
        this.SecondName = SecondName;
        this.EMail = EMail;
    }
}