What size chain do I need??

I just got a new rear sprocket for my 00 RM250.

Stock was 13t up front and 48t in the rear. When I got the bike it had a 49t rear. I just ordered a 50t rear.

The stock chain is a 520 112 link chain and the rear axle is about half way back (13/49) in terms of adjustment.

Do I buy another 112 link chain or do I need a 114? 116?

Thanks

Wear. I will order a new front as well.