Calculation for subtract public holidays between vacations requested by the employer

I have an app 1 where I list all of nacional holidays, and another app The employer requested their holidays to the company.

(NOTA: I need to calculate subtract the days of nacional holidays from App 1 within the vacaction requested by the App 2.)

APP 2 ( I used this calculation : https://help.podio.com/hc/en-us/community/posts/202828487-Calculating-workdays.) Works perfect :-)

APP 1: List national holidays.

I look forward to hearing from you.

Katherine.