class Person:
    counter=0
    def __init__(self,name,age):
        Person.counter+=1
        self.name= name
        self.age = age
    def __str__(self):
        return  self.name +" is "+ self.age+" years old"
    @classmethod
    def from_string(cls,personstr):
        a=personstr.split(",")
        return Person(a[0],a[1])