Rihanna & Lady GaGa Team Up

Yeh so supposedly this is suppose to Rihanna's dis song to Chris Brown ft Lady Gaga, its called "Silly Boy" ummm i think its cool... i guess. and oh yeh the hook is a line stolen from one ciara song i enjoy "My Love" and the line is "see boy you had a keeper, but you didnt know how to treat her"

can you tell when rihanna is singing and when gaga is singing?

listen to song here