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

Difficulty: Very easy (0)

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

Difficulty: Easy (0)

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

Difficulty: Very easy (0)

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

Difficulty: Very easy (0)