[R] Unique rows

[Lanre Okusanya]

hello all,

I have a dataset where the subjects are duplicated. How do I subset
such that I can get only I row/subject.

aa<-c(1,1,2,2,3,3,4,4,5,5,6,6)
bb<-c(56,56,33,33,53,53,20,20,63,63,9,9)
cc<-data.frame(aa,bb)

I would like to subset df(cc) such that I can get
aa bb
1 56
2 33
3 53
4 20
5 63
6 9

I know this should be fairly easy but I can't figure how to do it in a
dataframe and keep all my columns

Thanks