sub a{
	my($x1,$y1,$x2,$y2,$x3,$y3)=@_;
	$x2-=$x1;
	$y2-=$y1;
	$x3-=$x1;
	$y3-=$y1;
	abs($x2*$y3-$x3*$y2)/2;
}
($x1,$y1,$x2,$y2,$x3,$y3)=glob<>;
for$a(0..3){
	for$b(0..3){
		for$c(0..3){
			$r=a
				$x1+($a==0)-($a==1),
				$y1+($a==2)-($a==3),
				$x2+($b==0)-($b==1),
				$y2+($b==2)-($b==3),
				$x3+($c==0)-($c==1),
				$y3+($c==2)-($c==3);
			$z=$r if $z<$r;
		}
	}
}
print$z;