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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very hard (0)

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

Difficulty: Very easy (0)