3	5	4					7
				1			3
	5					2
			6					2
			4
		6
							7
					1

Difficulty: Medium

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

Difficulty: Easy

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

Difficulty: Medium

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

Difficulty: Medium