#1번, B835193 석채원
def getGrade(score):
    if score>=90:
        return 'A'
    elif score>=80:
        return 'B'
    elif score>=70:
        return 'C'
    elif score>=60:
        return 'D'
    else:
        return 'F'
    
def main():
 score = int(input("점수를 입력하세요: "))
 print("성적은", getGrade(score), "입니다")
main()
