Every student except Charles and Norman passed the course. The only student who was dismissed was Norman. Every student retook the course if and only if he or she was not dismissed and did not pass. Charles is not Norman. Therefore, exactly one student retook the course. (Sx: x is a student; Px: x passed the course; Dx: x was dismissed; Rx: x retook the course; c: Charles; n: Norman)

Derive the conclusion of the following arguments. Use conditional proof or indirect proof as needed.