Eight persons sit in a row. Four persons face north and the other four face south. There are three persons sitting between A and B, and one of these t...

Eight persons sit in a row. Four persons face north and the other four face south. There are three persons sitting between A and B, and one of these two sits at an end of the row. C sits second to the right of B, and B faces north. D and B face the same direction but are not seated next to each other. E sits third to the left of D and faces the opposite direction to D. G sits third to the right of C. Both immediate neighbors of G face the same direction. H sits to the right of F. If all the persons rearrange their seating positions so that they sit in alphabetical order from the left end of the row (with their original directions unchanged), how many persons will remain in their original positions?