Hi,
From the single line in manoj's comments, i studied the following: Powerof concepts can be solved in 2:
1. bottom to top if brackets are explicitly mentioned.
2. top to bottom if no brackets are mentioned.
(before 4k+1 concept, this line is important. We may studied and forget or may not studied).
In your comments u simple say that powerof should come only from top to bottom. That's y confused. Now, i can come thru all ur comments once again and try myself. Thanks for manoj for reminding the basics and smart coder for new logic.