Count Of Maximum Consecutive Sellouts For Each Customer

I have a sheet that lists customers in column A and then each customers Distribution & Sales over a period of time. The spreadsheet then flags if the customer has sold out in any month. I now require a count of maximum consecutive sellouts for each customer. For example:

Customer A S/O S/O nil nil S/O
Customer B S/O S/O S/O nil nil
Customer C nil S/O S/O S/O S/O

In the above example Customer A would have 2, B 3 and C 4 sellouts. I'm looking at about 10K customers I require for each product.