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

Difficulty: Very easy (0)

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

Difficulty: Very hard (0)

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

Difficulty: Easy (0)

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

Difficulty: Very easy (0)