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

Difficulty: Easy (0)

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

Difficulty: Hard (0)

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

Difficulty: Very 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)