6			9	5
2				4		7
					7		6
	2				3		8
	6		9				3
	5		1
		9		6				2
		2	7			3

Difficulty: Very easy (0)

			9			7
3	9		7
	1	6
	6		5		3
			8		4		2
						8	4
					8		1	6
		9			5

Difficulty: Very easy (0)

				3			8
	8				6
	2				7		9	1
		2					3
	1			9			4
	6					9
6	5		4				7
			6				5
	7			1

Difficulty: Very easy (0)

	1				8
3			2	1
				5	6	3
1	2						4
			6		2
	4						2	3
		1	8	9
				2	3			9
			4				8

Difficulty: Hard (0)