//-----
 public override void visit(Employee emp)
 {
     totalDays += emp.getVacDays();
     try {
         Manager mgr = (Manager)emp;
         totalDays += mgr.getBonusDays();
     }
     catch (Exception) {}
 }
 //-----
 public override void visit(Employee emp)
 {
     totalDays += emp.getVacDays();
 }