Very difficult. After finally figuring it out, I started giving different tasks to try out. For example, no two pieces of the same color can touch. Or try to move all black stones vertically or horizontally without touching each other. The possibilities go on and on. I like to challenge my brain as it is supposed to help it stay young. (I'm almost 80 but I'm still trying.) It's a lot of fun and a good conversation starter when it's on the table for others to see and try.
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