#Class ke Andar Dusre Class ka object 

class School:
  def __init__(self):
    self.Students=[]
  def 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 CalculateGrade(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 Display(self):
    print(self.name)
    print(self.grade)

schl=School()
for i in range(3):
  name=input("Enter Your Name : \n ")
  marks=int(input("Enter Your marks : \n "))
  std1=Student(name ,marks)
  std1.CalculateGrade()
  schl.addStudent(std1)

topper=schl.topper()
print("Topper is : ")
print(topper.name)