Well, after double check the drawings and the measures, I was wrong in the way I was thinking of the diagonals itself instead the sides. And in addition I was taking into account just a side of the wall, which means to add or subtract half of the thickness, but of course that means the full thickness when it comes to the full wall with its two sides.
In conclusion, I was all messed up myself.
Nevermind.----------------------------------------
If a long walk every day were healthy, mailmen would be immortal.
