3
1. a
   1. aa
      1. aaa
         1. aaaa
            1. aaaaa
               1. aaaaaa
               2. aaaaab
               3. aaaaac
            2. aaaab
2. b
3. c
4. d
5. e
6. f
7. g
   1. ga
      1. gaa
   1. gb
      1. gba
      2. gbb
      3. gbc
         2. skipped one
            3. skipped some more