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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Easy (0)