In a building there are thirteen flats on three floors-II, III and IV. Five flats are unoccupied. Three managers, two teachers, two lawyers and one doctor occupy the remaining flats. There are at least three flats on any floor and not more than six flats on any floor. No two persons of the same profession stay on any floor. On the second floor, out of four flats, one occupant is the lawyer
It has only one neighbour. One teacher lives one floor below the other teacher. The doctor is not the neighbour of any of the lawyers. No flat is unoccupied on the third floor.
How many flats are there on the third floor ?