Hi if each line is unique : 1store,1sku, 1 value :
you add a new column type Integer value 1 then
you can use for example tAggregateRow component , choose the column wich contain store name as group by and choose the column you add just before with sum option in Operations of taggregateRow.
FInally you have just to compare if the new column have the value of your list 1 row number.