我想以以下方式对python中的项目进行排序

Question

import os
os.chdir("C:\\Users\diodi\\OneDrive\\Desktop\\September2018")
for i in os.listdir("C:\\Users\diodi\\OneDrive\\Desktop\\September2018"):

    if len(i)==16:
     print(i)

for i in os.listdir("C:\\Users\diodi\\OneDrive\\Desktop\\September2018"):

    if len(i) == 17:
        print(i)

如果我在同一个for循环中使用了两个if循环，就会像这样1,10,11,12 ... 2,20,21..3,30,4,5,6

这是我想要的输出，是否有更好的方法按此顺序对它们进行排序？

1  september.pdf
2  september.pdf
3  september.pdf
4  september.pdf
5  september.pdf
6  september.pdf
7  september.pdf
8  september.pdf
9  september.pdf
10  september.pdf
11  september.pdf
12  september.pdf
13  september.pdf
14  september.pdf
15  september.pdf
16  september.pdf
17  september.pdf
18  september.pdf