# grade.py - ian alexander skelskey - 10/7/22

grade = input("Enter a number grade from 0-100: ")
grade = int(grade)
if grade < 60:
	print("F")
elif grade < 70:
	print("D")
elif grade < 80:
	print("C")
elif grade < 90:
	print("B")
else:
	print("A")
print("\n")