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

Difficulty: Super easy (0)

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

Difficulty: Very hard (0)

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

Difficulty: Super easy (0)

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

Difficulty: Very easy (0)