How many persons are there between P and Z?

Study the following information carefully and answer the question given below: There are eight people P, Q, R, S, W, X, Y and Z are living in a 8 floor Building on different floors from top to bottom (such as ground floor is numbered as 1 and top floor is numbered as 8) but not necessarily in the same order. W lives immediately above the floor on which R lives but not on an even numbered floor. S lives on the floor which is a prime number but not on the 3rd floor. X lives immediately below the floor on which Q lives. The person lives between P and R is not more than three and not less than two. P live on the topmost floor. There is one person living between the floors on which W and S lives. Z lives immediately above the floor on which Q lives.