class Student:
    students = []

    def __init__(self, name, scores):
        self.name = name
        self.scores = scores
        Student.students.append(self)

    def get_average(self):
        return sum(self.scores) / len(self.scores) if self.scores else 0

    @classmethod
    def get_class_average(cls):
        if not cls.students:
            return 0

        total = 0
        count = 0

        for student in cls.students:
            total += sum(student.scores)
            count += len(student.scores)

        return total / count if count > 0 else 0

s1 = Student("철수", [90, 80, 70])
s2 = Student("영희", [85, 95, 100])
s3 = Student("민수", [60, 75, 70])
print("학급 전체 평균:", Student.get_class_average())

students = [s1, s2, s3]

for student in students:
    print(f"{student.name}의 평균 점수: {student.get_average():.2f}")