Alec and Ellie are the only detectives in the town of Broadchurch. Assume efficient production. Each has 10 hours in a day to allocate between conducting interviews and completing paperwork. They work independently and have to decide whether they will trade paperwork files for interviews.

Alec takes 11 hours to complete one interview or 35 hours to complete one file of paperwork.

Ellie takes 16 hours to complete one interview or 12 hours to complete one file of paperwork.

Consider the price of 1 interview in terms of paperwork files. What is the LOWEST price at which a trade between Alec and Ellie takes place? Enter a number only.