No, it' not a trick question. And it's possible to solve without having a brain like Mr Einstein!
(Accidently I've found this riddle two weeks ago, so I would feel like cheating.)
Graphical spoiler for Stitchawl
Spoiler:
On this site:
http://www2.fh-rosenheim.de/gki/pdf/pdf.htm in the right column you will find a file "Aufgaben & Lösungen 1-4". Open the pdf file and on pages 6-8 you see this problems solved in pictures. The text around is in German but I think one can guess the logic nonverbally, "Regeln" is rules and gives the number of the sentence.