******** fig6.27 **********

	/* For merge1, H1 has smaller root, H1 and H2 are not NULL */

	PRIORITY_QUEUE
	merge1( PRIORITY_QUEUE H1, PRIORITY_QUEUE H2 )
	{
/*1*/		if( H1->left == NULL )	/* single node */
/*2*/			H1->left = H2;	/* H1->right is already NULL,H1->npl is already 0*/
		else
		{
/*3*/			H1->right = merge( H1->right, H2 );
/*4*/			if( H1->left->npl < H1->right->npl )
/*5*/				swap_children( H1 );

/*6*/			H1->npl = H1->right->npl + 1;
		}
/*7*/		return H1;
	}