@echo off
setlocal

:poll
echo.
set "name="
set "age="

:name
set /p name="Enter name: "
if not defined name goto:name
if "%name%"=="12345" goto:result

:age
set /p age="Enter age: "
if not defined age goto:age
if "%age%"=="12345" goto:result

set /a cnt+=1

if %age% leq 20 set "persons_young_%cnt%=%name%:%age%" && goto:poll
if %age% leq 60 set "persons_middle_%cnt%=%name%:%age%" && goto:poll
if %age% geq 61 set "persons_old_%cnt%=%name%:%age%" && goto:poll

:result

echo.
echo young persons:
for /f "tokens=2,3 delims==:" %%i in ('"2>nul set persons_young_"') do echo %%i %%j

echo.
echo middle persons:
for /f "tokens=2,3 delims==:" %%i in ('"2>nul set persons_middle_"') do echo %%i %%j

echo.
echo old persons:
for /f "tokens=2,3 delims==:" %%i in ('"2>nul set persons_old_"') do echo %%i %%j