Hotel front desk schedule four people have 6 days and 8 hours off. How to arrange it?

It is fair to shift in a certain order. \ x0d \ ABC \ x0d \ DAB \ x0d \ CDA \ x0d \ BCD \ x0d \ DAB \ x0d \ CDA \ x0d \ BCD \ There is a cycle every four days, and one person can take a day off every four days. Everyone works in the morning, middle and evening classes on average, but there will be an extra day off every month. According to the number of people in your post, make sure there are people in each class. That class can't come because of something urgent, so the next one will be postponed. Who is the top who is the top.