1	11		5					6
9	6											12		3
			10	7		11	16
		14		13			1		8		2	16
														2
	13	10				5	6	1	11			14
7						12		5
	5			15							10			13
	15			16							1			12
							11		4						14
			8			2	14	6	13				15	1
	10
			13	12		1		2			8		3
								13	9		6	15
	8		5											10	7
						8					5		13	6

Difficulty: Hard (0)

					3	16
		4		6	14	7					8	16
14		11		4		1									10
										16	9			13
	4				9		2			3			16		11
			11		13	15									4
9	13													14
									5		16
				10		14
	11													2	12
1									12	6		13
5		9			1			7		4				15
	3			1	10
10									7		6		3		2
			12	15					2	1	3		8
									8	9

Difficulty: Very easy (0)

			10			9			7		15			14
1				6		11						10
2	4	9		5
	15	3				4
9		15			5		2
		6			3		16				9		2		8
			11								14	9			12
								8			2
				11			10
16			14	3								15
3		8		14				6		13			7
								4		12			16		2
									5				11	6
											6		9	5	10
			9						3		1				7
	5			16		3			11			1

Difficulty: Easy (0)

									3					15
								12	11		4		9	6
	1		4					8
						10	3					8
	4				5	13	11			9
7			5		9			6					10	13
	13		2	1										7
6		1	8										14
		14										16	4		12
	6										2	3		9
	12	10					8			7		13			11
					14			4	9	16				1
			14					11	7
							13					12		4
	11	8		14		1	4
	2					11

Difficulty: Easy (0)