Seven teachers M, N, O, P, Q, R and S take different number of tuitions. P takes more tuitions than S. M takes more tuitions than Q. R takes the second highest number of tuitions. The number of tuitions that O takes is less than only that of four teachers. N takes less tuitions than P but more than M. Q takes the least number of tuitions. S takes the second lowest number of tuitions.
In terms of the number of tuitions taken, who is between N and S?