After evaluating the arrivals of patients to an emergency department of the Dublin Hospital, the medical director identified the number of doctors needed per each time period. Now, she needs to develop an optimal schedule of doctors assigned to the emergency department. Each time period may be covered by staff attendants (full-time doctors) and medical interns (residents) that just finished their medical programs. The attendants have three shifts of 8 hours each, starting from 8 am, 4 pm and 12 am. The interns' schedule includes two 12-hour shifts starting from 8 am and 8 pm. The hourly cost is $130 per attendant and $44 per intern. Help the medical director to identify the optimal schedule of doctors and interns in the emergency department