class school:

  def __init__(self):
    self.students = []

  def find_topper(self):
    topper = self.students[0]
    return topper

  def addStudent(self,student):
    self.students.append(student)
  

class student:

    def __init__(self, name, marks):
        self.name = name
        self.marks = marks
        self.grade = ""

    def showGrade(self):
        if self.marks < 40:
            self.grade = 'D'
        elif self.marks < 60:
            self.grade = 'C'
        elif self.marks < 80:
            self.grade = 'B'
        else:
            self.grade = 'A'

    def displayGrade(self):
        print(self.name, 'your grade is:')
        print(self.grade)


sch = school()

for i in range(1):
    name = input("Enter your name: ")
    marks = int(input("Enter your marks: "))

    std = student(name, marks)
    std.showGrade()
    sch.addStudent(std)

topper = sch.find_topper()
print(topper.name)
print(topper.marks)
topper.displayGrade()