10	1	9	7
7					2		5
			9					1
				10		2		5
		4							6
5							4
	2		3		5
	6					8
		6		1					7
						7	9	4	8

Difficulty: Easy (0)

						10		5
	3		4
1	9	6	7				4
			6						1
5					10	9		4
	6		5	10					4
9						6
		4				7	6	8	10
						2		9
	5		2

Difficulty: Hard (0)

8	6			10				3
	3							4
10					2	5
				3
7							6	1	10
4	8	1							5
					10
			5	9					1
	9							8
	4				6			2	7

Difficulty: Easy (0)

9							8		4
		5		7
				3		2		8
5		10
		4					10		6
7		9					1
							3		1
	9		1		7
					2		9
1		3							2

Difficulty: Easy (0)