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

Difficulty: Very hard (0)

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

Difficulty: Super easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)