Please tell me something about P4? I liked F9, I have heard that P6 is so volume based, so I decided to opt for P4, but I have heard that not only the paper is difficult / basicly I like maths/ but the examiner make this paper literally non-passable. Please, for those ones that have tried it- please advise- if you could choose- would you do it again or you would choose some different paper. ?