Seven persons, P, Q, R, S, T, U and V, live in a seven-storey building, but not necessarily in the same order. Bottommost floor is numbered as 1 and the topmost floor is numbered as 7. P lives on the odd numbered floor. R lives three floors above P. Q lives below P but not just below P. U lives just above S. V doesn't live below S. Who lives on the second floor?