class Student:
    class_count =   # 类属性
    def __init__(self, name):
        self.name = name  # 实例属性
        Student.class_count += 1

s1 = Student("Alice")
s2 = Student("Bob")
s1.class_count = 1
print(Student.class_count)
print(s1.class_count)
print(s2.class_count)