The Volunteers of The Avengers Club

Mr. $X$ is the general secretary of the club, $'Avengers'$. Tomorrow there will be a fair in the club premises. He has $N$ number of volunteers with him. Each volunteer is sitting at a stall and also no two volunteers can sit at a single stall. Mr. $X$ wants to communicate only with the volunteers at the boundary stalls. He knows the locations of all the stalls. But tomorrow he will be so busy wi