class Student(object):
    def __init__(self, name, gender):
        self.name = name
        self.__gender = gender

    def set_gender(self, gender):
        if gender in ['man', 'woman']:
            self.__gender = gender
        else:
            raise RuntimeError('Gender Type Error!')

    def get_gender(self):
        return self.__gender

s = Student('xiaoming','man')
s.set_gender(input('input gender：\n'))
print(s.get_gender())