Assume that you want to register in a program where you need to study 8 courses

The names of the 8 courses are a, b, c, d, e, f, g and h. Some courses are pre-requisite of some other course. The details are given here

Course a is pre-requisite of course c and d

Course b is pre-requisite of course d

Course c is pre-requisite of course d and e

Course e is pre-requisite of course h

Course f is pre-requisite of course e and g

Course g is pre-requisite of course h

Find the topological sorting/ordering of these courses