I would like to write the code to construct the following variable.

Cost stickiness it = ๐‘™๐‘œ๐‘”(ฮ”Cost / ฮ”๐‘†๐‘Ž๐‘™๐‘’)๐‘–,๐œ1โ€“๐‘™๐‘œ๐‘”(ฮ”Cos t / ฮ”๐‘†๐‘Ž๐‘™๐‘’)๐‘–,๐œ2

๐œ1,๐œ2 โˆˆ {๐‘กโˆ’1,โ€ฆ,๐‘กโˆ’5} where ๐œ1 is the most recent of the last five years with an increase in sales and ๐œ2 is the most recent of the last five years with a decrease in sales;

Does anyone know how to write this code?

Thank you in advance!!