sub DoStuff {
  my ($a, $b, $c) = (-1, -2, -3);
  if ($#_ == 2) {
    ($a, $b, $c) = @_;
  } elsif ($#_ == 1) {
    ($a, $c) = @_;
  } elsif ($#_ == 0) {
    ($b) = @_;
  };

  print "A= $a\n";
  print "B= $b\n";
  print "C= $c\n";
}