Answer the questions based on the information given below. Seven persons stay in 7 different floors of a building such that no two persons stay in same floor. The floors are numbered 1 to 7 respectively from bottom to top. At least 4 persons stay between U and P. Odd number of persons stays below U, who stays on a prime numbered floor. Three persons stay between Y and S such that Y stays above S. X lives immediately above Q. Z lives on an even numbered floor.
How many persons live between P and S?