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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very hard (0)