Paper-Title Serial Number Level

Oh woo woo, look dumbfounded, and write a manuscript>_<

The three-level structure of the directory:

Level 1: Chapter 1
Level 2: 1.1
Level 3: 1.2.1

Number sequence number level sequence:

First-level title number one, two, three,
second-level title number (1)
Third-level title number 1.
Fourth-level title number (1)
Fifth-level title number ①
Sixth-level title number A. Or (A)
Seven-level title number a . Or (a)