public class Datoexn3 {

  public static void main(String[] args) throws GalDato {
    Dato d1 = new Dato(1999, 13, 30);
    System.out.println(d1.isodato());
  }
}

class GalDato extends Exception {
  int aar, maaned, dag;

  GalDato(int arr, int maaned, int dag)
  { this.aar = arr; this.maaned = maaned; this.dag = dag; }

  public String toString() 
  { return "Fejl: Ulovlig dato " + aar + "-" + maaned + "-" + dag; }
}

class Dato {
  private int aar, maaned, dag;

  Dato(int aar, int maaned, int dag) throws GalDato {
    if (ok(aar, maaned, dag)) 
      { this.aar = aar; this.maaned = maaned; this.dag = dag; }
    else
      throw new GalDato(aar, maaned, dag);
  }

  public String isodato()
  { return aar + "-" + tocifre(maaned) + "-" + tocifre(dag); }

  private static boolean ok(int aar, int maaned, int dag) { 
    return maaned >= 0 && maaned <= 12 
      && dag >= 1 && dag <= dageimaaned(aar, maaned); 
  }

  private static int dageimaaned(int aar, int maaned) {
    int[] dage = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};    
    if (skudaar(aar) && maaned == 2)
      return 29;
    else
      return dage[maaned-1];
  }

  private static boolean skudaar(int aar)
  { return aar % 4 == 0 && aar % 100 != 0 || aar % 400 == 0; }

  private static String tocifre(int n)
  { return (n < 10 ? "0" + n : "" + n); }
}