<s>[INST] When 12 students presenting research papers at a conference are randomly assigned to 4 sessions of 3 students each, a total of $12 \cdot 11 \cdot 10 = 1320$ orderings are possible for the first session alone. This number represents the first 3 of a 12-element permutation of the students. In general, for n students assigned to r sessions of m students each (with $n = rm$), the number of orderings for the first session is given by $n \cdot (n-1) \cdot ... \cdot (n-m+1)$. This expression is denoted by $P(n,m)$.[/INST]