#!/usr/bin/perl -w
$x = $ARGV[0];
$y = $ARGV[1];
$x = posneg($x);
$y = posneg($y);

$p = .5*($x+$y-2)*($x+$y-1)+$x;

print "$p\n";

sub posneg {
my($N) = $_[0];
return (2*$N) if ($N > 0);
return (-2*$N+1); # for $N>=0
}
