I need a formula that will do the following:

Column A contains order numbers. I want to count all the orders, however, if
an order number appears more than once, I only want it counted once. In
addition, if an order was cancelled, the word "cancelled" would be in Column
C for the cancelled order. I don't want any cancelled orders included in the
count.

Col. A Col. C
1
1
7 Cancelled
9
12 Cancelled
12 Cancelled
14

In this situation, the sum of the order numbers would be 3.

Thanks in advance,
Howard