A high school has 5000 lockers. At the beginning all the lockers are closed. The first student gose down the line opening every locker. The second student gose down the line closing every other locker starting at locker number two. The third student gose down the line to every third locker starting at locker number three. If the locker is closed, he or she opens it. If it is opened, he or she closes it. This process continues with the fourth student, fifth student, and so on.How mwnay lockers are opened after 5000 students?