static void Main(string[] args)
{
Student st1 = new Student("George", "Malandris", "4dd4d");
st1.print();
Student st2 = new Student("Panagiotis", "varamentis", "4dd4d46");
st2.print();
Student st3 = new Student("stavros", "", "4dd4d45");
st3.print();
Student st4 = new Student("Aggeliki", "Papantoniou", "d455a55555a");
st4.print();
Worker w1 = new Worker("George", "Malandris", 50, 8);
w1.print();
Worker w2 = new Worker("Panagiotis", "varamentis", 150, 30);
w2.print();
Worker w3 = new Worker("stavros", "", 1, 8);
w3.print();
Worker w4 = new Worker("Aggeliki", "Papantoniou", 100, 0);
w4.print();
}