How to count number by differenct group

Hello,

Good Morning.

I have a report in BO, and I am trying to achieve the following function, but I don;t know how to do it. I have a table below..

And this table is sorted by depart time and badge time;

And what I want to do is: all 541-1 show 1 for dispatch order( because it is the first number show up, and then 541-5 show 2)

Another trick thing is there is a another 541-1 at the bottom with different depart time, but it should show besed on how many unique badge number above+1)

If you have any idea, please teach to how to do it and thanks so much

Frank