# Write your Python code here

#input
marks = input("Enter your marks")
print (marks)

marksInt = int(marks)


grade = ''

if marksInt < 40:
   grade = 'D'
elif marksInt <60:
   grade = 'C'
elif marksInt <80:
   grade = 'B'
else:
   grade = 'A'
print (grade)