'''

 # 语法1:

 '''

 if 条件1:

     code1

     code2

     code3

     ......

 '''

 # age=18

 # if age != 18:

 #     print('你好啊小伙子')

 #     print('加个微信吧...')

 # print('other code...')

 # 语法2:

 '''

 if 条件:

     code1

     code2

     code3

     ......

 else:

     code1

     code2

     code3

     ......

 '''

 # age=18

 # sex='male'

 # wuzhong='human'

 # is_beautiful=True

 #

 # if age > 16 and age < 22 and sex == 'female' and \

 #         wuzhong == 'human' and is_beautiful:

 #     print('开始表白...')

 # else:

 #     print('阿姨好,我逗你玩呢...')

 # 语法3:

 '''

 if 条件1:

     if 条件2:

         code1

         code2

         code3

     code2

     code3

     ......

 '''

 # age = 18

 # sex = 'female'

 # wuzhong = 'human'

 # is_beautiful = True

 # is_successful = True

 #

 # if age > 16 and age < 22 and sex == 'female' and wuzhong == 'human' and is_beautiful:

 #     print('开始表白...')

 #     if is_successful:

 #         print('在一起')

 #     else:

 #         print('阿姨再见....')

 # else:

 #     print('阿姨好,我逗你玩呢...')

 # 语法4:

 '''

 if 条件1:

     子代码块1

 elif 条件2:

     子代码块2

 elif 条件3:

     子代码块3

 elif 条件4:

     子代码块4

 .........

 else:

     子代码块5

 '''

 score = input('your score>>: ')

 score=int(score)

 if score >= 90:

     print('优秀')

 elif score >= 80:

     print('良好')

 elif score >= 70:

     print('普通')

 else:

     print('很差')