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 displayGrade(self):    
    print(self.name)
    print("Grade - ")
    print(self.grade)


students = []

for i in range(3):
    name = input("Enter Name: ")
    marks = int(input("Enter Marks: "))

    st = Student(name, marks)
    st.calculateGrade()
    students.append(st)

for i in range(3):
  students[i].displayGrade()