+510 Five workers $A,$ $B,$ $C,$ $D,$ and $E$ at a coffee stand are working out a schedule for the next $10$ days. The schedule must satisfy the following conditions:
* There must be exactly two workers every day, and every pair of workers must be scheduled on some day.
* If two workers are scheduled on some day, then one of them must work the next day.
How many different possible schedules are there?
