[백준] 9498 - 시험 성적 (파이썬)

a = int(input())

if a >= 90:
    print("A")
elif a >= 80 and a < 90:
    print("B")
elif a >= 70 and a < 80:
    print("C")
elif a >= 60 and a < 70:
    print("D")
else :
    print("F")