Eight people, D, E, G, H, M, N, Y and Z are sitting in a straight line, facing north. Y sits at one of the extreme ends of the line. Only three people sit between Y and Z. E sits second to the right of Z. Only three people sit between E and D. G sits at one of the positions to the left of D but not at an extreme end of the line. M is not an immediate neighbour of Z. N sits second to the right of H. How many people sit to the left of H?