Baekjoon 9498번(python)

score = int(input())

if(score >= 90 and score <= 100):
    print('A')
elif(score >= 80 and score <= 89):
    print('B')
elif(score >= 70 and score <= 79):
    print('C')
elif(score >= 60 and score <= 69):
    print('D')
else:
    print('F')