[R] where to get the "leaps" package

[Yong Wang]

Dear all
I am supposed to use Mallow's Cp creterion to select a model which require
a "leaps" package. the version right now I am using is R
1.7.1(os:windows), the "leaps" package is not included. please let me know
how and where
can I get this package and add it to the current version, any caution on
adding this package is highly appreciated.
thank you 

best