@echo off

rem counter variable
set tempvar=1

rem get volumes that are optical drives
echo list volume > diskpart_input.txt
diskpart /s diskpart_input.txt > temp.txt
find /n "-ROM" temp.txt > temp2.txt

for /f "tokens=3,4 delims= " %%a in (temp2.txt) do (
if %tempvar%==1 (
echo tempvar is %tempvar%
set tempvar= 2
echo changed tempvar to %tempvar%
echo select volume= %%a > tempscript.txt
echo assign letter=R >> tempscript.txt
type tempscript.txt
echo Assigning drive R
diskpart /s tempscript.txt
) else (
echo select volume= %%a > tempscript.txt
echo assign letter=S >> tempscript.txt
echo Assigning drive S
diskpart /s tempscript.txt
goto end )
)

:end
del /f temp.txt
del /f temp2.txt
del /f diskpart_input.txt
del /f tempscript.txt
pause