def main():
    data_storage = [{'school_class': '4a', 'scores': [3, 4, 4, 5, 2, 3, 5]},
                    {'school_class': '4b', 'scores': [3, 2, 2, 5, 2, 5]},
                    {'school_class': '5a', 'scores': [3, 4, 5, 5, 2, 2]},
                    {'school_class': '4b', 'scores': [5, 4, 2, 5, 2]},
                    {'school_class': '6a', 'scores': [4, 4, 4, 3, 5, 2, 2]},
                    {'school_class': '6b', 'scores': [3, 3, 5, 5]}]

    classes_grade = {item['school_class']: (sum(item['scores']) / len((item['scores']))) for item in data_storage}
    school_grage = sum(classes_grade.values()) / len(classes_grade.values())

    print(f"School summary grade is {school_grage:.1f}")
    print("Class summary grade are:")
    for name_class, grage_class in classes_grade.items():
        print(f"{name_class}: {grage_class:.1f}")


if __name__ == "__main__":
    main()