import os

class Student:
    def __init__(self, name_, age_, grades_ ):
        self.name = name_
        self.age = age_
        self.grades = grades_
    def add_grade(self, grade):
        self.grades.append(grade)
    def average(self):
        sum = 0
        for i in range(len(self.grades)):
            sum += self.grades[i]
        sum /= len(self.grades)
        return sum
    def show_info(self):
        print("Name:", self.name, "Age:", self.age, "Grades:", self.grades)
class MaleStudent(Student):
    def __init__(self,  name_, age_, grades_ ):
        self.gender = "Male"
        self.name = name_
        self.age = age_
        self.grades = grades_
    def show_info(self):
        print("Gender: ", self.gender, "Name:", self.name, "Age:", self.age, "Grades:", self.grades)
    def show_gender(self):
        print("Gender: ", self.gender)

x = Student("Van", 20, [100, 100, 98, 100])
x.show_info()
print(x.average())
x.add_grade(90)
x.show_info()
print(x.average())
y = MaleStudent("Van", 20, [100, 100, 98, 100])
y.show_info()
y.show_gender()