Complicated challenging tricky formidable demanding demanding tough murderous major sophisticated rugged sweaty tall testing tough critical intricate stiff uphill exhausting backbreaking exacting elusive agonizing choose-and-shovel intricate major grueling effortful intense herculean arduous hellacious laborious troublesome gruelling brutal problematic included hairy bruising abstract... https://erickwromf.blogdomago.com/36562956/the-greatest-guide-to-killer-sudoku