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

Difficulty: Super easy (0)

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

Difficulty: Super easy (0)

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

Difficulty: Easy (0)

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

Difficulty: Easy (0)