>>997159each vertex on the structure represents a carbon
a carbon can will only make 4 bonds
that is say, there will be 4 lines in total for each vertex on the structure
you just count the existing bonds and fill in bonds with hydrogen to make 4:
if there is only 1 bond shown explicitly for that carbon, then you have to fill it with 3 bonds with hydrogen to make 4 bonds total
if there are only 2 bonds drawn on that carbon, then you need to fill in 2 bonds with hydrogen
if only 3 bonds drawn for that carbon, you need to put in 1 hydrogen
if there's 4, then that carbon is full up, and there will be no hydrogens attached
