A two-story building uses a simple elevator to carry its tenants. A switch is located on each floor to call...

A two-story building uses a simple elevator to carry its tenants. A switch is located on each floor to call the elevator: ↑ switch on the first floor and ↓ switch on the second floor. Two switches are available inside the elevator; one to go to the first floor ( button) and the other to go to the second floor ( button). No other facilities such as emergency stop, “open door”, “close door”, etc. are supported by the elevator.