# Write your Python code here

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.grade)

st1 = student("st1",40)
st2 = student("st2",55)
st3 = student("st3",70)
st4 = student("st4",85)
st5 = student("st5",75)

st1.calculateGrade()
st1.displayGrade()

st2.calculateGrade()
st2.displayGrade()

st3.calculateGrade()
st3.displayGrade()
 
st4.calculateGrade()
st4.displayGrade()

st5.calculateGrade()
st5.displayGrade()