if you really are this lazy and want an easiest way out than i think you should cover at least 6/8 topics for paper A and paper2 will require a lil more effort. you have a choice to leave at maximum 2 topics.and which ever topic you leave in choice you will still have to go through it to learn definitions and to have a basic knowledge of that topic.
But one important thing is to be kept in mind, what ever topics you are covering , you should not leave any stone unturned about those topics.