How do you create this algorithm using BFS (Breadth-first search)?

Franklin Airlines is planning its network for the new year, which includes flights, airports, and most importantly, its crew. All crew members are assigned to an airport crew base, but to operate a crew base is expensive. As a result, flights must be between an airport with a crew base, and one without. Your job is to develop a system that places crew bases based on a given network plan, which consists of p airports and f flights. Devise an algorithm that designates each airport with or without a crew base such that each flight can be adequately crewed. If the network plan canno be adequately crewed, your algorithm must identify this. The algorithm must run in O(p+f) time - justify that this is true. (10 points)