How to calculate the number of vacation days, based on the difference between “End Date” and “start date”.

Hello, I am new with Creatio using “No code”. Trying to created, a business process when is triggered calculate the number of vacations day, based on the difference between “End Date” and “start date”. The result should be filled into “Vacation days” column in the request table.

Please see attached screen print that I created this Vacation Mini page.

Thank you!