If all the persons live according to the English alphabetical series from top to bottom, then how many persons remain unchanged in their position?

Answer the questions based on the information given below. Eight persons viz. U, V, W, X, Y, Z, A and B are living in an eight-storey building, but not necessarily in the same order. The bottommost floor is numbered as 1 and the floor immediately above it is numbered as 2 and so on. Not more than one person lives on the same floor. The consecutive alphabetically named person doesn’t live on the adjacent floors of the building. Y lives on an odd-numbered floor and three floors below Z. A lives between Y and Z. Only two persons live between A and B who doesn’t live on the bottommost floor. X lives on an even-numbered floor. The number of floors above X is the same as the number of floors below U. W lives three floors below
V.