Hi, i want to count rows, but only when i write something.
In column A i want the number to appear when i write something in column B

ex

A B
1 nrt crt product
2 1 something
3 2 something
4 nothing



When i write something in B2, i need number 1 to apeear in A2, and start
counting in A3, A4,...etc, but only when i write something in the next cell

If i delete B3 or another filled cell in column B, the count to dissapear.
Can it be done?

THANK YOU IN ADVANCE.