count/ countif/ calculate/ filter

Hi,

I am building a dashboard to track response rates to emails.

I have a number of columns in the table, and the ones i need to use are Received Time, and Subject.

The table is sorted by received time, oldest to newest.

I want to add a column that wil put a 1 against the earliest instance for each Subject.

I would like to then do the same for the second, third, fourth etc, but this would be an added bonus.

Can anyone help?