Sort n numbers between [0,n^2 - 1] in O(n)?

Possible Duplicate:
An array of length N can contain values 1,2,3 … N^2. Is it possible to sort in O(n) time?

Given n numbers at the range [0,n^2 -1] how can we sort them in O(n) run time ?

I have a feeling that the solution involves radix sort ,but I'm still missing something.

The n numbers are integers .

Any ideas ?

REMARK: not homework!

Regards