Why is the 2nd Chiral Carbon of Cephalexin R?

[Lo.Lee.Ta.]

Why is the 2nd chiral carbon of cephalexin molecule R? I thought the N has first priority, then the Carbon with the double bond to the O would be second (b/c has no H), and the Carbon bonded to the S would be third priority b/c it has a hydrogen, and of course, H is fourth... But then it would be S if that was the case... Why is it R?

 

[Lo.Lee.Ta.]

Never mind. Well, not that anyone was going to answer anyway.

But the chiral carbon in question is bonded to an S and an N. S and N have a greater atomic weight than O. So the H doesn't matter.

The Carbon bonded to the S and N is second priority.