class App {
   public static void main(String[] args) {

//    Employee.get_population();
//    Person.get_population();

//    Person p1 = new Person(2,3,1972);
/*
      p1.print();
      p1.get_population();
*/

//    Employee e1 = new Employee(2,3,1972,1,1,1995);
/*
      e1.print();
      e1.get_population();

      e1.date.print();
      System.out.println(e1.population);
*/
      System.out.println("/////////////////////////////////");
/*
      p1 = e1;

      p1.print();            // instance method call
      p1.get_population();   // class (static) method call

      p1.date.print();                   // field access
      System.out.println(p1.population); // static field access

      System.out.println(Person.population);
                                  // static field explicit access
      System.out.println(Employee.population);
                                  // static field explicit access
*/
   }
}


class Date {      // no static members
   int day;
   int month;
   int year;
   Date(int d, int m, int y) {
      day = d;
      month = m;
      year = y;
      System.out.println("A new Date was created " + day + "   " +
                         month + "   " + year);
   }

   void print() {
      System.out.println("  " + day + "   " + month + "   " + year);
   }
}

class Person {
// both static and non static members, static block initialization
   static int population;
   Date date;
// static block initialization
   static { System.out.println("The initial population is: " +
                               population); }

   Person(int d, int m, int y) {
      date = new Date(d,m,y);
      population++;
      System.out.println("A new person was born in ");
      date.print();
   }

   static int get_population() {
      System.out.println("People population is " + population);
      return population;
   }

   void print() {
      System.out.println("Printing birth date ");
      date.print();
      System.out.println("Age should be non zero");
   }
}

class Employee extends Person { // both static and non static members,
                                // static block initialization
   static int population;
   Date date;
   static { System.out.println("The initial Employee population is: " +
                               population); }

   Employee(int d1, int m1, int y1, int d2, int m2, int y2) {
      super(d1,m1,y1);
      date = new Date(d2,m2,y2);
      population++;
      System.out.println("A new Employee in ");
      date.print();
   }

   static int get_population() {
      System.out.println("Employee population is " + population);
      return population;
   }

   void print() {
      System.out.println("Printing employee birth date ");
      super.date.print();    // inherited field date
      System.out.println("Printing employment date ");
      date.print();
      System.out.println("Age should be over 18");
   }
}