Eight friends P, Q, R, S, T, U, V and W are sitting in two lines, with four friends sitting in each line. Both the lines are facing north. The four persons in the back line are exactly behind the four persons in the front line. P is between T and W. Q is just behind T. Q, who is to the immediate left of S, is also at one of the corners in the back line. R is between S and U. Who is sitting between P and V?