@echo off
rem call :a1 yyyymmddhhmmss yyyymmddhhmmss result
call :a1 19700101000000 20380119031407 s
echo %s%
pause
goto :eof

:a1
setlocal
set /a b=10000,c=100
call :a2 1 %1 & call :a2 2 %2
call :a3 y1 m1 d1 d1 & call :a3 y2 m2 d2 d2
set /a s1+=h1*3600+n1*60,s2+=h2*3600+n2*60,s3=(d2-d1)*86400-s1+s2
endlocal & set /a %3=%s3%
goto :eof

:a2
set a=%2
set /a y%1=1%a:~0,4%-b,m%1= 1%a:~4,2%-c,d%1= 1%a:~6,2%-c
set /a h%1=1%a:~8,2%-c,n%1=1%a:~10,2%-c,s%1=1%a:~12,2%-c
goto :eof

:a3
set /a y=%1,m=%2,d=%3,m+=(y-1)*12,d+=(m-1)*31
set /a a=m+9,d+=a/48-a/1200+a/4800,b=12
set /a %4=d-a/b*3-(m+7)/b-(m+5)/b-(m+2)/b-m/b