while True:
    ten=input("输入分数:")
    try:
        score=eval(ten)
        if type(score)==int:
            break
    except:
            print("请输入数字")
            pass
if score > 100 or score <0:
    print("分数不合理")
elif score >= 80:
    print("优秀")
elif score >= 70:
    print("良好")
elif score >= 60:
    print("及格")
else: print("不及格")