php, 262 bytes

Result

AC

Duration

515ms

Code [DL]

<?php [$a,$b,$c]=explode(" ",readline());[$d,$e,$f]=explode(" ",readline());[$g,$h,$i]=explode(" ",readline());[$j,$k,$l]=explode(" ",readline());$g-=$a;$h-=$b;$i-=$c;$j-=$a;$k-=$b;$l-=$c;echo(($e-$b)*($i*$j-$g*$l)+($f-$c)*($g*$k-$h*$j)+($d-$a)*($h*$l-$i*$k))/6;

stdin

46 78 09
73 47 13
69 82 89
09 47 61

stdout

33192

stderr

strace