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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Medium (0)