A concierge in a ritzy hotel booked seven guests, even though he had only 6 rooms available.

When the guests arrived, he did his best to make up for his mistake.

He took the first guest from the lobby and led him to the first room. He asked the next guest to wait for few minutes in the first room while he helped the others. Then he took the third one and showed him to the second room. Next he led the fourth guest to the third room, the fifth guest to the fourth room, and the sixth guest to the fifth room. Then he returned to the first room, picked up the seventh guest who was waiting for him there and led him to the sixth room.

So, everything was fine, right?