Four.

I will not cheat, I will not take or look for hints, I'm not listening to what other people have achieved and I will not compete. I want this to be fun. I don't do crosswords, sudoku or anything else like those ghastly wastes of life. I hate all kinds of games. But this one is a piece of genius, an amazing mix of mental intrigue and sheer luck, with a good degree of annoyance thrown in. I want to give it five or ten minutes over my mid-morning flat white. It feels good for my brain.