SharePoint Designer counting the number of list items

Hi All,

I am writing a SharePoint 2010 workflow in which if an item is added to listA (PersonA, department, fiscal year etc fields)  an item is created in listB. Easy enough :)

But here is the actual problem. If another item added to listA with the same name and same fiscal year, i dont create an item in list B, I just increase the Count field on listB. If the item added has a different person or different year I will create an item in listB.

All the above logic is figured out.

MY QUESTION: For the first time when an item is added in listA, i dont have to compare anything, just create that item in listB. For which i have to know this is the first item in listA. Basically

if(no of items on listA = 1)

Create item in listB

How can I count the number of items in listA?

Thanks in advance