Madara low difficulty. No explanation needed
Doubtful low difficulty mention.
Explanation: Itachi is/was a prodigy, as he was Anbu level at such a young age; besides that observation; he DID KILL all his clan (speculation that he had help IIRC.) ...and by kill his clan, I mean had the KILL to take each clan member out (speculation that they didn't fight back I also believe -- UNLESS proven otherwise lol).
So, in closing:Madara with HIGH Diffaculty, unless Madara himself was also a prodigy (speculationagain I would assume would be the only proof on this lol)