1.
The set S={1,2,3,…,12}S = \{1, 2, 3, \dots, 12\} is to be partitioned into three sets A,B,CA, B, C of equal size. Thus A∪B∪C=SA \cup B \cup C = S, A∩B=B∩C=C∩A=∅A \cap B = B \cap C = C \cap A = \emptyset, then the number of ways to partition SS are