@Test
public void testYES(){

	node8.left = node6;
	node8.right = node11;
	
	node6.left = node4;
	node6.right = node7;
	
	node4.left = node4_4;
	node4.right = node5;
	
	node11.left = node9;
	node11.right = node12;
	
	node9.left = node9_9;
	
	Assert.assertTrue(BinarySearchTree.checkBST(node8));
}