Eight trainees A, B, C, D, E, F, G and H are sitting in a straight row, all facing north. H sits third from the left end of the row. Exactly two persons sit between H and C. A sits immediately to the right of C. F sits second to the left of A. D is an immediate neighbour of both H and F. B and E sit at the two extreme ends of the row. G sits somewhere to the left of E. Based on the given information, how many persons sit between G and F?