class Person:
    counter=0
    def __init__(self,first_name,last_name,age):
        self.__first_name=first_name
        self.__last_name=last_name
        self.__age=age
        self.__email=self.__first_name+"."+self.__last_name+"@"+Person.domain_name
        Person.counter+=1
    def __str__(self):
        return self.__first_name+" "+self.__last_name+" is "+str(self.__age)+" years old and her email id is "+self.__email
    def fullname(self):
        return self.__first_name+" "+self.__last_name
    @property
    def age(self):
        return self.__age
    @age.setter
    def age(self, value):
        self.__age=value