in a computer programming school, students allowed to take multiple computer language courses during one semester. the final exam for each course is set to a 2- hour exam from 6 pm to 8 pm. to finish all exams for all students, what is the minimum number of nights required for all students to finish all their exams. (no student is allowed to take two of their course exams at the same night.) here are all students and courses they are taken.