MathDB

n

men and one woman are in the meeting room with

n+1

chairs, each of them having their own seat. Show that the following two number of cases are equal.
(1) Number of cases to choose one man to get out of the room, and make the left

n-1

men to sit to each other's chair.
(2) Number of cases to make

n+1

people to sit to each other's chair.

Problem Statement