Find length of time between latest and last instance formula

Hi,

I have some data containing date columns and a column showing a 1 to represent in stock and a 2 to represent out of stock. I am trying to find a formula that allows me to measure the time in days for a specific item between the occurrence of a 2 (going out of stock) and then the next occurrence of a 1 (when it comes back into stock). The same item may come in and out of stock several times so it must treat each pairing of a 2 and 1 as its own instance. I have filled in the first example in the attached workbook. You will see a tab called pivot also, I thought this might be part way to a solution but I think its a dead end, feel free to disregard.

Not sure if this is actually possible but would be great to know either way. If anyone can help it will be much appreciated.

Wow, thank you, that worked perfectly. I have found a second problem though, happy to start a new thread if that is the correct protocol. Now I know the number of days I need to know how many fall into each month. I have added some helper columns in the spreadsheet to do this and started with a array formula but got lost. Is it possible do you think? For instance if it goes out of stock 20th Jan and back in 10th Feb then it would need to say 11 days in the Jan column and 10 in the Feb column.

Like I say, you have already helped me greatly so more than happy to start a new thread and I am thankful for your input.

Now that is something is something special, thank you very much!!! Really appreciate your time on this.

Thanks for sharing your knowledge.