After getting vaccinated, students will be able to return to in-person classes next semester. There will be n students, s1; s2; :::; sn, return to in-person classes, and there will be k in-person classes. Each in-person class consists of several students and a student can be enrolled in more than one in-person class. We need to select one student from each in-person class and the maximum times a student is selected should be less than m. Design an algorithm that decides if such a selection exists, or not.