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

Difficulty: Very hard (0)

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

Difficulty: Very easy (0)

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

Difficulty: Hard (0)

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

Difficulty: Very easy (0)