Six persons i.e P, Q, R, S, T and U are living in a Six floor building in which the topmost floor is numbered as 6 and the bottommost floor is numbered as 1 but not necessarily in the same order. R lives on a even numbered floor which is a perfect square of a number and immediate below U. U is not living adjacent to T and S, who lives on an odd prime numbered floor. There Four floor gap between T and Q. How many floors is there between T and S?