class Student: 
    def __init__(self, name, age, grade):
        # instance variables
        self.name = name
        self.age = age
        self.grade = grade #0 - 100

    def get_grade(self): 
        return self.grade

class Course: 
    def __init__(self, name, max_students): 
        self.name = name
        self.max_students = max_students
        self.students = []
    
    def add_student(self, student): 
        if len(self.students) < self.max_students: 
            self.students.append(student)
            return True
        return False

    def get_average_grade(self): 
        value = 0
        for student in self.students: 
            value += student.get_grade()
        return value / len(self.students)


s1 = Student("Tim", 19, 95)
s2 = Student("Bill", 19, 75)
s3 = Student("Jill", 19, 65)

biology = Course('biology', 2)
biology.add_student(s1)
biology.add_student(s2)
print(biology.get_average_grade())

    