70 students take a quiz in Discrete Structures. Stephen collects the papers and then redistributes them to the class so that students grade other students. a) How many ways can this be done so that no one receives his or her own quiz? b) How many ways can this be done so that exactly 5 students receives his or her own quiz? c) Now suppose Stephen also passes back 70 assignments to be graded. How many ways can Stephen pass one assignment and one quiz to each student, so that no one gets either their own assignment or their own quiz?