class Student(object):

    def __init__(self, name, score, gender):
        self.__name = name
        self.__score = score
        self.__gender = gender

    def print_score(self):
        print('%s: %s' % (self.__name, self.__score))

    def set_name(self, name):
        self.__name = name

    def set_score(self, score):
        if 0 <= score <= 100:
            self.__score = score
        else:
            raise ValueError('bad score')

    def set_gender(self, gender):
        if gender != 'male' and gender != 'female':
            raise ValueError('bad gender')
        else:
            slef.__gender = gender

    def get_name(self):
        return self.__name

    def get_score(self):
        if self.__score > 90:
            return 'A'
        elif self.__score >= 80:
            return 'B'
        elif self.__score >= 70:
            return 'C'
        elif self.__score >= 60:
            return 'D'
        else:
            return 'F'

    def get_gender(self):
        return self.__gender

yang = Student('yang gao', 66, 'male')
hannah = Student('hannah chen', 100, 'female')