A small school has 100 students who occupy three classrooms: $A, B,$ and $C$. After the first period of the school day, half the students in room A move to room B, one-fifth of the students in room B move to room $C,$ and one-third of the students in room $C$ move to room A. Nevertheless, the total number of students in each room is the same for both periods. How many students occupy each room?