excel formula

I need an excel formula to tell me how many individual times a process can be started and stopped based on a number to trigger and a number to finish process e.g. 1,2,2,3,4,4,5 - If I start process at 2 and finish at 4, in this range it can happen twice, but we want to find times it can happen with only 1 concurrency, so correct result I need is 1. I need formula so i can specify X start and Y finish and it will give me result. I upload test file