Hi guys! I have a question regarding the Nanjing Subway S1 line.

I'm about to fly from Lukou International Airport in a couple weeks and I would appreciate to get some sort of insight and this site is the first one I come across with actual recent answers/questions.
My question is if the metro line S1 runs directly from the South Railway Sation all the way to the aiport (and vice versa), or if I will have to transfer first? (Like take line 1 or 3 and then transfer to Line S1). Thanks in advance!