Does mcgill look at the global r-score or just program-specific r-score?

My dream is to go into med-school at McGill when I am finished CEGEP. My problem is that McGill requires an R-Score of 32 and up. I currently have an R-Score of 27... after a year of arts. Now that I am switching into sciences, do I have a chance at med-school? Will McGill look at my entire R-Score, which will undoubtedly be brought down by my year of arts? Or will they just look at how well I did in the science program?