sub RGB {
  my ($red,$green,$blue) = @_;
  return $red + 256 * $green + 65536 * $blue;
}

print RGB(0,0,0) . "\n";
print RGB(255,255,255) . "\n";
print RGB(255,0,0) . "\n";
print RGB(0,255,0) . "\n";
print RGB(0,0,255) . "\n";