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

Difficulty: Very hard (0)

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

Difficulty: Super easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)