Regarding the (s, S) inventory model, Please show how I can use the given events and modify and write up the pseudo-code to incorporate the following?

Two modes of delivery: If the inventory level falls below s (I < s) (and no orders of any kind are in progress) and is also below s/2 (I < s/2), then an Express order is made ensuring delivery exactly L = 2 (days) later. But an express order of size Y costs more: k(Y ) where k is a given function with k(y) > c(y), y > 0. If s/2 I < s, then a regular delivery at cost c(Y ) with lead time L H takes place as usual. (Where E(L) > 2, and V ar(L) > 0.)