i want to give input like {a,b,c} and want o/p {{},{a},{b},{c},{a,b,c}}

I want a Clapton special edition black Fender Stratocaster.

You get me my stratocaster and I'll do your homework for you.

If that's not possible then maybe you should read the forum rules that you agreed to when you joined DaniWeb, including

"Do provide evidence of having done some work yourself if posting questions from school or work assignments"
http://www.daniweb.com/community/rules

Post what you have done so far and someone will help you from there.