@echo off
SETLOCAL EnableDelayedExpansion EnableExtensions
set tmpstr=
set text=%*
IF "%~1"=="" (set/p text= )
call :StrlenF "%text%" strlen
call :backstrF "%text%" %strlen% backstr
echo.
exit/b

:backstrF
    echo.

:proc_LOOP

set tmpstr=%tmpstr%!text:~%strlen%,1!


<nul set /p  tmpstr=!text:~%strlen%,1!

set /a strlen-=1
if !strlen! EQU -1 (set %3=%tmpstr% & exit /b)
goto :proc_LOOP
exit/b



:StrLenF ([in]str,[out]Length) 
:: -----------------------
:: Функция Нахождения длины строки /by Aскет/
:: -----------------------
    Set complen=0
    Set StringBuf=%~1
    If ""=="%~1" GoTo :EOF
    :StringLenLoop
    Set /A complen+=1
    Call Set StringChr=%%StringBuf:~%complen%%%
    set %2=%complen%
    If ""=="%StringChr%" GOTO :EOF
    GoTo :StringLenLoop
exit/b