Statement

Giorgio, famous university teacher, tomorrow is going to do the surveillance during his exam of Competitive Programming. In fact, even though the students are usually very honest, there is always someone that tries to cheat. To prevent it, Giorgio is studying a disposition for the students in the room that maximizes the distance between each student. The exam room is composed by R × C seats arranged in a rectangle of R rows and C columns. Giorgio wants his students to be arranged in rows and columns as well, but skipping some rows and some columns to space them out. Given a distance factor K, each student must be at least K seats away (K-1 seats in between) from the ones in his row and column. Help him find the maximum number of students that fit inside the classroom.