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

Difficulty: Very easy (0)

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

Difficulty: Easy (0)

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

Difficulty: Very hard (0)