class Person:
    counter=0
    def __init__(self,first_name,last_name,age):
        Person.counter+=1
        self.first= first_name
        self.last = last_name
        self.age = age
        self.email= first_name  + "."  + last_name +"@" +self.domain_name
    def __str__(self):
        return self.fullname() + " is " + str(self.age) + " years old and her email id is " + self.email
    def fullname(self):
        return self.first +" " +self.last