221100770044337700001111 221100770044337700001111 000000770000007700001111 000000770000007700001111 777777777777777700002222 777777777777777700002222 000066772200007700002222 000066772200007700002222 000033774400007700003333 000033774400007700003333 777777777777777700003333 777777777777777700003333 000000770000007700004444 000000770000007700004444 334400770055667700004444 334400770055667700004444 777777777777777700005555 777777777777777700005555 000000000000000000005555 000000000000000000005555 000000000000000000006666 000000000000000000006666 000000000000000000006666 000000000000000000006666 Sudoku with 6 colours on a 6x6 grid?