ABC Co. is providing transportation services during a five day conference. The manager of ABC Co. is attempting to schedule a work assignment for the buses. Each day ABC is required to provide day-long trips to two different locations. The minimum number of buses required for trip i in day j is bij where i ∈ {1, 2} and j ∈ {1, 2, 3, 4, 5}. ABC has imposed the condition that each bus works at most three consecutive days during the five days. Additionally, once a bus is assigned to trip i, then it must remain on the same trip i every day it works. ABC has K buses available. Formulate this problem to make a bus schedule minimizing the number of buses allocated for the conference.