I mean … damn it was hard. I had to pull out a pen and paper to solve it. Even then i was scribbling down numbers without even looking at the page.
Haha! Happened to me once. I tried like 1,2,2,3,1 but got me really confused. So I started to memorize positions like left right top and worked for me. I was worried at that time to think that I was too dumb for that.
Yes. I found it rather boring. 