Dumfries Industries is generating a materials requirement plan for the next six weeks. Here is its most current information:

Master Production Schedule:

Week:	1	2	3	4	5	6
Item A	10	0	50	50	0	10

Other Information:

Item	Items Parent	Items Lead Time	Items Lot Size	Items Current On-hand Inventory
A	None	1 week	lot for lot	10
B	A	1 week	20	20
C	A	1 week	20	40

How many levels does a product structure for Dumfries item A have? Please enter a whole number only, for example, 5.