files = Dir['*/*']
files.each do |old_path|
  old_dir = old_path.split('/').first
  next if old_dir.length < 12
  new_path = old_path.sub(%r[(.{3})(.{9})/(.{12})], '\1/\2\3')
  `mkdir -p #{$1}`
  `mv #{old_path} #{new_path}`
  if Dir[old_dir + '/*'].empty?
    `rm -r #{old_dir}`
  end
end