Hotel schedule

According to White Vinegar Eggs, it is illegal to spend 12 hours a day. Everyone works eight hours a day, takes a day off every four days and takes seven and a half days off every month. As follows:

Someone, from 8: 00 to 16 on the first day, from 0: 00 to 0: 00 on the second day and from 0: 00 to 8: 00 on the third day. Rest on the fourth day.

On the first day, A works in the morning shift, B works in the middle shift, C works in the evening shift, and D has a rest. The next day, D was on the morning shift, A was on the middle shift, B was on the evening shift, and C was off. On the third day, C is on the morning shift, D is on the middle shift, A is on the night shift, and B is off. On the fourth day, B is on the morning shift, C is on the middle shift, D is on the night shift, and A has a rest. Start another round on the fifth day.