Не работает валидация Python

Пишу класс на пайтоне и мне нужно сделать валидацию на поля класса решил сделать это сразу в конструкторе при помощи try-except шаманил шаманил, а выбивает ошибку на целочисленных значениях полей класса не понимаю в чем ошибка

class Employee:
    def __init__(self):
        self.surname = ""
        self.year = 0
        self.salary = 0
        self.company = ""
        self.city = ""
        self.birth_year = 0

    def __init__(self, surname, year, salary, company, city, birth_year):
        try:
            if surname.isalpha():
                self.surname = surname
            else:
                raise Exception()
        except Exception as e:
            print("Incorrect surname input!")
        try:
            int(year)
            if year.isdigit() and 0 < year < 100:
                self.year = year
            else:
                raise Exception()
        except Exception as e:
            print("Incorrect year input!")
        try:
            int(salary)
            if salary.isdigit() and 0 < salary < 100000:
                self.salary = salary
            else:
                raise Exception()
        except Exception as e:
            print("Incorrect salary input!")
        try:
            if company.isalpha():
                self.company = company
            else:
                raise Exception()
        except Exception as e:
            print("Incorrect company's name input!")
        try:
            if city.isalpha():
                self.city = city
            else:
                raise Exception()
        except Exception as e:
            print("Incorrect city's name input!")
        try:
            int(birth_year)
            if birth_year.isdigit() and 1950 < birth_year < 2000:
                self.birth_year = birth_year
            else:
                raise Exception()
        except Exception as e:
            print("Incorrect year of birth input!")

    def __str__(self):6
        print("{Surname:"+self.surname+";year:"+int(self.year)+";salary:"+int(self.salary)+";company:"+self.company+";city:"+self.city+";birth year:"+int(self.birth_year)+"}")


emp = Employee("Matcha", 20, 2000, "Epam", "Uzhhorod", 1999)
print(str(emp))

вот что выдает компилятор:

Incorrect year input!
Incorrect salary input!
Incorrect year of birth input!
Traceback (most recent call last):
  File "C:/Users/dell/PycharmProjects/untitled/Employee.py", line 99, in <module>
print(str(emp))
File "C:/Users/dell/PycharmProjects/untitled/Employee.py", line 95, in __str__

print({Surname:"+self.surname+";year:"+int(self.year)+";salary:"+int(self.salary)+";company:"+self.company+";c ity:"+self.city+";birth year:"+int(self.birth_year)+"}") AttributeError: 'Employee' object has no attribute 'year'