First of all thank for your reply.
If you not feeling good in helping in this issue you not have to.
Secondly, I am working on this one for a couple of days, in this point a small hints like the other guys gave here will only make my learning experience more complete.
Lets say that if you are stuck after you think about the solution for a very long time, if no one will ever help you and point you in the right direction you will never learn!!!