class People(object):
    def __init__(self,name,age):
        self.name = name
        self.age = age

    def info(self):
        print("Name: " + self.name + " Age: " + str(self.age))

class Employee(People):
    def __init__(self,name,age,pos,salary):
        super().__init__(name,age)
        self.__pos = pos
        self.__salary = salary

    def __getpos(self):
        return self.__pos

    def __setpos(self,pos):
        self.__pos = pos

    def __delpos(self):
        del self.__pos

    position = property(__getpos,__setpos,__delpos)

    def __getsal(self):
        return self.__salary

    def __setsal(self,salary):
        self.__salary = salary

    def __delsal(self):
        del self.__salary

    sal = property(__getsal,__setsal,__delsal)

    def info(self):
        People.info(self)
        print(" Position: " + self.__pos + " Salary: " +
              str(self.__salary))

class Teacher(Employee):
    def __init__(self,name,age,pos,salary):
        super().__init__(name,age,pos,salary)
        self._discipline = []

    def info(self):
        Employee.info(self)
        print(" Disciplines: " + " ".join(self._discipline))

    def adddis(self,dis):
        self._discipline.append(dis)

    def deldis(self,dis):
        try:
            self._discipline.remove(dis)
        except:
            print("There is no such discipline")



People1 = People("Ruslan",25)
People2 = People("Andrew",54)
Employee1 = Employee("Nikita", 28, "Manager", 69000)
Employee2 = Employee("Sasha", 32, "Banker", 120000)
Teacher1 = Teacher("Emil", 35, "IT", 58000)
Teacher1.adddis("Math")
Teacher2 = Teacher("Ivan", 27, "Geography", 29000)
members = [People1, People2, Employee1, Employee2, Teacher1, Teacher2]
for member in members:
    member.info()
for member in members:
    if member.age < 30:
        print(member.name)