Eight friends - S, T, U, V, W, X, Y and Z are sitting around a square table facing the centre. They sit in such a way that four of them sit at four comers of the square while four sit in the middle of each of the four sides. Only Z sits between S and X. S sits in the middle of one of the sides. V sits third to the right of X. Both Y and Z are immediate neighbours of S. T sits second to left of U. Who sits third to the left of X?