set txt="C:\scr\a.txt"
for /f "usebackq tokens=1,2,3,4,5,6,7,8 delims=, " %%i in (%txt%) do (
set /a X=%%j-%%i+%%l-%%k+%%n-%%m, po=%%p-%%o
)
set /a XX=X+po
echo %XX%