Consider n students with numbers 1,2,…,n standing in the order 1,2,…,n. Upon a command, any of the students either remains on his place or switches his place with another student. (Actually, if student A switches his place with student B, then B cannot switch his place with any other student C any more until the next command comes.)Is it possible to arrange the students in the order n,1,2,…,n−1 after two commands ? combinatoricsinvariantpermutationIMO ShortlistIMO Longlist