An investigator interviewed students to determine the performance of three drinks milk, coffee and tea. The investigator reported that students take all three drinks milk, coffee and tea; students take milk and coffee, students take coffee and tea, students take milk and tea, students take milk only, students take coffee only and students take tea only. Then the number of students who did not take any of the three drinks is
A positive integer is said to be good if there exists a partition of into disjoint proper subsets such that the sum of the numbers in each subset of the partition is How many good numbers are there?