Rearranging nested directory

I have a folder system with the structure below:

folderA 
- folder1
  - file1A.txt
- folder2
  - file2A.txt
- folder3
  - file3A.txt

folderB 
- folder1
  - file1B.txt 
- folder2 
  - file2B.txt 
- folder3
  - file3B.txt

I wish to change the order to make the numbered folder above the letter folders as:

folder1 
- folderA
  - file1A.txt
- folderB
  - file1B.txt

folder2 
- folderA
  - file2A.txt 
- folderB 
  - file2B.txt 

folder3 
- folderA
  - file3A.txt 
- folderB 
  - file3B.txt 

Here is a piece of code to construct a MWE of the initial directory structure:

import os 
import shutil
import string

root_dir = os.getcwd()
os.chdir('/home/alletro/Tc-97/tools')
os.makedirs('master', exist_ok=True)
os.chdir('master') 
master_dir = os.getcwd()
top_tier = [f'folder{i}' for i in range(1,4)]
second_tier = [f'folder{i}' for i in list(string.ascii_uppercase)[:4]]
for folder in top_tier: 
    os.chdir(master_dir)
    os.makedirs(folder, exist_ok=True) 
    os.chdir(folder)
    fold_dir = os.getcwd()
    for sub_folder in second_tier:
        os.chdir(fold_dir)
        os.makedirs(sub_folder, exist_ok=True) 
        os.chdir(sub_folder)
        os.mknod("newfile.txt")
os.chdir(root_dir)

I have found a solution that gets me a dictionary of the directory tree:

def get_directory_structure(rootdir):
    """
    Creates a nested dictionary that represents the folder structure of rootdir
    """
    dir = {}
    rootdir = rootdir.rstrip(os.sep)
    start = rootdir.rfind(os.sep) + 1
    for path, dirs, files in os.walk(rootdir):
        folders = path[start:].split(os.sep)
        subdir = dict.fromkeys(files)
        parent = reduce(dict.get, folders[:-1], dir)
        parent[folders[-1]] = subdir
    return dir

I'm however struggling to see where to take it from here.

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