Determine oldest combi of year and quarter and put related value to cell Hi there

Hi there, can anyone help me out?
In a data table (column A-F) I want :
1. determine what is the oldest recent year/quarter per customer and
2. copy the year/quarter (YYYQ) and paste it in column N. The value in the cell related to this year/quarter combi must be paste in column O

In column L the most recent combi is already filled, but i do not succeed how to make the formule for the oldest combi works for the whole range (N3-N5)
I have attached a file ito make clear what I mean.


Help is much appreciated!
Rgds, Robert