public class Person{

  private string name;
  private Date dateOfBirth;
  private Date? dateOfDeath;

  public Person (string name, Date dateOfBirth){
    this.name = name;
    this.dateOfBirth = dateOfBirth;
    this.dateOfDeath = null;
  }

  public string Name{
    get {return name;}
  }

  public Date DateOfBirth{
    get {return dateOfBirth;}
  }

  public int DayAge(){
    return new Date(2007, 9, 25).DayDifference(dateOfBirth);   
  }                                                            

  public override string ToString(){
    return "Person: " + name + " " + dateOfBirth;
  }

}