my($a,$b,$c,$d,$e,$f,$g,$h,$i,$j,$k,$l)=map{/\d+/g}<>;print+(($g-$a)*(($k-=$b)*($f-=$c)-($e-=$b)*($l-=$c))+($j-$a)*($e*($i-=$c)-($h-=$b)*$f)+($d-$a)*($h*$l-$k*$i))/6