@echo off&setlocal enabledelayedexpansion

for /f "tokens=1* delims=:" %%a in ('findstr /n . a.txt') do set #%%a=%%b&set n=%%a

for /l %%a in (1,1,!n!) do (

  for /l %%b in (%%a,1,!n!) do (

  if !#%%b! gtr !#%%a! (

  set v=!#%%a!

  set #%%a=!#%%b!

  set #%%b=!v!

  )

 )

  echo,!#%%a!

)

pause