Which language to learn for facebook games...?

I already know a lot of turbo c++ and all the oo concepts.Now i'm thinking of learning vc++ or c# .My aim is to first create a small simple 2d game like maybe something like that copter game(which is written in flash).I'd also eventually like to try my hand at creating some facebook game or app.Would i be do that with c++ or would it be better if i try to learn flash.Would it be more difficult to with c++/#.I understand most of these browser based games are made mostly in flash.But i figure it'd be more easier and useful to know vc++/c#.So what do you guys suggest i learn..?Thanks.